The invention relates to the technical field of radar circuit fault detection and diagnosis, specifically to a radar signal unit performance test and fault diagnosis system based on a general test platform. The system comprises a general test platform, a test procedure set, an interface connection module, an interface test adapter and a signal processing unit to be tested, the general test platform includes general test instruments and hardware resources including a test procedure set, a programmable power supply, a spectrometer, a signal generator, a digital oscilloscope, a digital triple-purpose meter, a digital I/O, a communication interface, a multichannel ADC and a multichannel DAC, and the test platform is connected with the interface test adapter through the interface connection module. By adoption of a system architecture of the general test platform plus the interface test adapter, the system has very strong universality and expandability, allows multiple equipment to share one test platform, and the interface test adapter adopts a hardware architecture of FPGA+ARM, and has very strong universality, expansibility and reconfigurability.