Based on the analysis of signal transmission mechanism of track circuit combined with its electrification characteristics, this paper proposes a new method of adding track signal acquisition points to realize fault location of track circuit compensation capacitor and estimate its residual life. Firstly, a hidden semi-Markov model of each compensation capacitor acquisition point is constructed by combining historical data with simulation test data, and the realtime operation status of compensation capacitor is monitored by the trained hidden semi-Markov model. Secondly, through the analysis of track circuit compensating capacitor operation data offset state, the normalized shunt current of each monitoring point is analyzed by safety offset distance, the leakage location of compensation capacitor beyond the safe offset state is carried out, and the residual life of compensation capacitor is estimated by combining the monitoring data with the hidden semi-Markov model after training. Finally, combined with the simulation test data, the rail acquisition point of compensating capacitor can be used to locate the leakage of compensating capacitor and estimate its residual life, and the accuracy of residual life estimation is more than 90%, optimizing the maintenance mechanism of compensating capacitor.