Aiming at the problem that the current detection method can’t meet the needs of the maintenance of the search-radar power supply, a multi-channel testing and diagnosis system based on CPCI bus is designed. The system uses AD210 chip to isolate the measured signal, and uses the CPCI8622 multi-function acquisition card to convert analog voltage signals into digital signals. At last, the digital signals are transmitted to the PC industrial control computer through the CPCI bus, in addition, analyzed and judged by the test software. The experiment results show that the system has the characteristics of convenient operation, portability, high precision, fast and accurate fault diagnosis, and the system realizes the function of parameter online testing and fault diagnosis, and meet the test requirements of radar power in a variety of environments.