Journal of Electronic Systems Xiaochun Wu, Guanggang Ji 8 1 2018 http://www.dline.info/jes/fulltext/v8n1/jesv8n1_2.pdf The interference with the track circuit signal is more and more complex under the condition of high-speed and heavy haul, how to detect the signal parameters of track circuit more accurately is becoming an important issue. Firstly, the harmonic interference of the traction current is analyzed, and the harmonic current component of the traction current under the consideration of the power frequency drift and actual measurement are given. Then, due to the track circuit frequency shift signal (FSK signal) uses the frequency parameters to transmit control information. Therefore, through improving the spectrum resolution to improve the reliability of the signal detection, and combing the advantages of ZFFT (Zoom Fast Fourier Transform) algorithm with multiple modulation in the field of signal spectrum local refinement, the ZFFT algorithm with multiple modulation is proposed to detect the frequency signal of the track circuit. This algorithm refines the interested local signal spectrum of the whole signal spectrum to improve the spectral resolution, which can find and eliminate the interference signal frequency. Finally, the simulation is carried out, and the simulation results show that the frequency shift signal detected by this method can meet the error standard of signal detection and improve the reliability of track circuit signal detection.