The stability and reliability of highprecision timefrequency signal is an important basis for modern navigation. It directly affects the accuracy of system time and navigation results. To solve the problem, the integrity monitoring method for physical time frequency signal has been researched on. In this paper, based on the proposed method, a highprecision timefrequency signal integrity monitoring system has been constructed using the UTC (NTSC) in National Time Service Center of Chinese Academy of Sciences. The system can realtime monitor the performance and the integrity of signal, immediately response to the trouble, resolve the problem and provide the highprecision physical signal more stability and reliability. The integrity monitoring method is verified and applied in many navigation systems and time frequency measurement systems.