Magnetoresistive sensor can be widely used in modern transportation field, such as the vehicle positioning and navigation system, vehicle detection system, and intelligent transportation system. In order to improve the efficiency of magnetoresistive sensor, we synthesized La0.8Sr0.2MnO3polycrystalline bulks at different sintering temperatures and investigated their DC and AC transport properties in this work. As a result, all samples showed insulator–metal(I–M) phase transition, and the transition temperature(TI–M) shifted to higher temperature with the increase of sintering temperature. The TI–Mmeasured at different AC frequencies was smaller than that measured at DC condition, which implied that the I–M phase transition was suppressed at AC frequencies. The resistivity measured at high AC frequencies was larger than that measured at low AC frequencies, which could be attributed to the change of the magnetic penetration depth(d). However, the room-temperature AC-magnetoresistance(MR) at low frequencies was much larger than that at high frequencies and room-temperature DC-MR. These findings demonstrate that reducing the AC frequency is an effective way for enhancing the room-temperature MR, which can be used to promote the efficiency of magnetoresistive sensor. In order to improve the efficiency of magnetoresistive sensor, we synthesized La0.8Sr0.2MnO3polycrystalline bulks at different sintering system. temperatures and investigated their DC and AC transport properties in this work. As a result, all samples showed insulator-metal (I-M) phase transition, and the transition temperature (TI-M) shifted to higher temperature with the increase of sintering temperature The TI-Mmeasured at different AC frequencies was smaller than that measured at DC condition, which implied that I-M phase transition was suppressed at AC frequencies. The resistivity measured at high AC frequencies was larger than that measured at low AC frequencies, which could be attributed to the change of the magnetic penetration depth (d). However, the room-temperature AC-magnetoresis tance (MR) at low frequencies was much larger than that at high frequencies and room-temperature DC-MR. These findings demonstrate that reducing the AC frequency is an effective way for enhancing the room-temperature MR, which can be used to promote the efficiency of magnetoresistive sensor.