Abstract： To decrease the processing time and reduce the system complexity of surface acoustic wave(SAW) torque sensor, a fast timedomain demodulation method based on the frequency response characteristic of SAW resonator was designed. The SAW response characteristic was analyzed, and a signal truncation and denoising method were designed. The period of received was obtained by finding zero cross points. The operational frequency band was found according to the relation between the higher frequency and the period of the received signal. The resonant frequency of SAW sensor was obtained by estimating the spectrum of the signal with the maximum period. The proposed method acquires only one channel signal which reduces the complexity of the hardware system of SAW interrogator. The processing periods are completed in the timedomain which simplifies the demodulation algorithm. For a single scanning cycle, the executing time is appoximately 521 ms for the proposed method while that of the traditional method is 828 ms, which verifies the proposed method.