In order to improve the technology maintenance efficiency, the radio fault diagnosing system uses a PXI test unit as the hardware platform. Design reasoning software platform based on the fault tree. Then carry out fault rational reorganization, reasoning, and judgment, deduce the correct result, and locate fault in board-level (that is the minimum alterable unit). The result shows that the system is high automation degree and easy to operation, which can realize module, fast and automatic testing for radio station fault “board-level location”.