The PCM-FM (pulse code modulation-frequency modulation) telemetry system is widely used in military satellites and aerospace telemetry owing to its exceptional polarization resistance and robust anti-interference capabilities. The implementation of the PCM-FM telemetry system was focused based on TPC (Turbo product code) channel coding technology. The improved Chase Ⅱ algorithm was employed for demodulating the system, and it was compared with a baseline algorithm and the theory model to evaluate its performance. The results show that the proposed Chase Ⅱ algorithm has a lower error rat then the baseline algorithm and close to the theoretical model. The accuracy of the improved algorithm is verified through network simulations.