Based on the analysis of factors affecting transient temperature field of aircraft fuel tank and coupled heat transfer mechanism,a mathematical model of transient coupled heat transfer,including the dynamic change of fuel quality,the internal heat transfer,the external aerodynamic convection and the radiation heat transfer,is established. Taking the aerodynamic convection and radiation heat transfer outside the tank as the third kinds of thermal boundary conditions for the thermal analysis of the fuel tank,calculation of internal and external coupling heat of fuel tank is decoupled. Thermal network method combined with hierarchical dynamic grid is used to deal with the fuel consumption,and carry on the heat transfer analysis of the fuel tank. The numerical method for the transient temperature field of aircraft fuel tank is established. Through the simulation calculation,the transient temperature distribution of the fuel tank under different flight conditions is obtained,and the influence of the fuel mass and the external thermal environment on the temperature field is analyzed. Based on the analysis of factors affecting transient temperature field of aircraft fuel tank and coupled heat transfer mechanism, a mathematical model of transient coupled heat transfer, including the dynamic change of fuel quality, the internal heat transfer, the external aerodynamic convection and the radiation heat take the aerodynamic convection and radiation heat transfer outside the tank as the third kinds of thermal boundary conditions for the thermal analysis of the fuel tank, calculate of internal and external coupling heat of the fuel tank is decoupled. with hierarchical dynamic grid is used to deal with the fuel consumption, and carry on the heat transfer analysis of the fuel tank. Through the simulation calculation, the transient temperature distribution of the fuel tank under different flight conditions is obtained, and the influen ce of the fuel mass and the external thermal environment on the temperature field is analyzed.