According to the basic relations of wheel/rail interaction with spectrum analysis method and considering the area of contact between the wheel and rail,the wheel/rail coupled vibrations excited by the small-scale roughness of the running surfaces of the wheel and rail are studied.The formulas of the space-averaged spectra of vertical and lateral vibration level of the wheel and rail are presented.Not only the vertical impedance and lateral impedance of steel rails,but also the radial impedance and axial impedance of wheels are successfully deduced.In the analysis of the steel rails′ vertical impedance,considering the sleepers′ quality and using the model of double-layer continuous resilience foundation beams,the rails are divided into Euler Beams and Timoshenko Beams.In the analysis of the steel rails′ lateral impedance,the rails are regarded as double structure.The rail heads are considered as Timoshenko girders considering shearing force and rotation and the webs are considered as spring and damp associating heads and foots.In the analysis of the wheel impedance,the wheel is simplified as an elastic circle loop,which taking the rigidity of web plate into consideration.The tread is regarded as an elastic loop,and the web plate is regarded as a spring component connecting wheel tread and wheel axle.Based on the wheel/rail coupled vibration research,considering the effects of the ground reflection the prediction expressions for the sound pressure level spectrum of the wheel/rail rolling-noise are given by means of the application of the structural sound radiation theory.In order to demonstrate the accuracy of this expression,the calculation results of wheel/rail high-frequency response and wheel/rail noise are compared with the test results in authorized reference.And the wheel/rail rolling-noise from existed railways in our country are predicted and measured.The numerical results and the measured ones agree well.With this existing model of wheel/rail rolling noise,the wheel/rail noise frequency,distance and speed characteristics are simulated and analyzed in this thesis.It shows that the wheel/rail noise spectrum distributes in a wide frequency range between 200～4 000 Hz,among which wheel vibration noise dominates between the 500～1 700 Hz frequency bands.Below 500 Hz or above 1 700 Hz frequency bands,wheels noise is the primary source.Among the total rail vibration noise,the rail vertical vibration noise takes the leading stand below 2 200 Hz frequency bands,while above 2 200 Hz frequency bands the dominant noise sources are rail′s vertical and lateral vibrations.Otherwise among the total noise of wheel,the dominant noise source is wheel axial vibration below 1 800 Hz frequency range,and the wheel radiant vibration is chief above 1 800 Hz.The effects on wheel/rail rolling noise are quantitatively studied with this model changed in the parameters which include roughness magnitude,wheel and rail parameters.Conclusions are drawn as follows: the roughness magnitude increasing expedites wheel/rail rolling-noise to rise radically within the frequency range of 200～4 000 Hz.It is beneficial for the reduction of wheel/rail rolling-noise to decrease the wheel radius,increase the thickness of wheel web,mass of wheel tread and rigidity of padding plate blank properly. According to the basic relations of wheel / rail interaction with spectrum analysis method and considering the area of ​​contact between the wheel and rail, the wheel / rail coupled vibrations excited by the small-scale roughness of the running surfaces of the wheel and rail are studied The formulas of the space-averaged spectra of vertical and lateral vibration levels of the wheel and rail are presented. Not only the vertical impedance and lateral impedance of steel rails, but also the radial impedance and axial impedance of wheels are successfully deduced. the analysis of the steel rails’ vertical impedance, considering the sleepers’ quality and using the model of double-layer continuous resilience foundation beams, the rails are divided into Euler Beams and Timoshenko Beams. In the analysis of the steel rails’ lateral impedance, the rails are as as double structure. the rail heads are considered as Timoshenko girders considering shearing force and rotation and the webs are considered as spring and damp associating heads and foots.In the analysis of the wheel impedance, the wheel is simplified as an elastic circle loop, which takes the rigidity of web plate into consideration. tread is regarded as an elastic loop, and the web plate is seen as a spring component connecting wheel tread and wheel axle. Based on the wheel / rail coupled vibration research, considering the effects of the ground reflection the prediction expressions for the sound pressure level spectrum of the wheel / rail rolling-noise are given by means of the application of the structural sound radiation theory. In order to demonstrate the accuracy of this expression, the calculation results of of wheel / rail high-frequency response and wheel / rail noise are compared with the test results in authorized reference. And the wheel / rail rolling-noise from existed railways in our country are predicted and measured. numerical results and the measured ones agree well. Current this existing model of wheel / rail rolling n oise, the wheel / rail noise frequency, distance and speed characteristics are simulated and analyzed in the first thesis. It shows that the wheel / rail noise spectrum distributes in a wide frequency range between 200-4000 Hz, among which wheel vibration noise dominates between the 500 ~ 1 700 Hz frequency bands.Below 500 Hz or above 1 700 Hz frequency bands, wheels noise is the primary source. Among the total rail vibration noise, the rail vertical vibration noise takes the leading stand below 2 200 Hz frequency bands, while above 2 200 Hz frequency bands the dominant noise sources are rail’s vertical and lateral vibrations. Other than among total noise of wheel, the dominant noise source is wheel axial vibration below 1 800 Hz frequency range, and the wheel radiant vibration is chief above 1 800 Hz. These effects on wheel / rail rolling noise are quantitatively studied with this model changed in the parameters which include roughness magnitude, wheel and rail parameters. Conclusions are drawn as follows: th e roughness magnitude increasing expedites wheel / rail rolling-noise to rise radically within the frequency range of 200-4000 Hz. It is beneficial for the reduction of wheel / rail rolling-noise to decrease the wheel radius, increase the thickness of wheel web mass of wheel tread and rigidity of padding plate blank properly.