The abrasion of a crosshead bushing is one of the important reasons for the failure of the compressor under normal circumstances. To ensure the safe and efficient operation of the compressor, it is necessary to monitor the temperature of the bushing in real time to determine the abrasion. For complex working conditions in petrochemical industry, a wirelessly coupled fiber-Bragg-grating (FBG) sensor is proposed and designed to wirelessly transmit optical signals, thereby realizing the extraction of bushing’s temperature signals. However, in order to solve the problem of excessive demodulation temperature difference caused by the U-type signal at the center wavelength generated during a dynamic operation, the insertion-loss threshold is used to reduce the temperature change from 4 ℃ to less than 0.1 ℃. This improves the accuracy of temperature demodulation and realizes the wireless monitoring of temperature.