The article introduced the structure and technology method of the auto test system based on PXI bus, for the core equipment of the aircraft telemetry system, requiring high work reliability. The article detailed the key technology about PCM decoding, data recording and real-time display. The validation of the final technology index was realized by computer making real time analysis and post analysis to the data. At present, the system was validated adequately in actual project application; it will be to enhance test efficiency of the corresponding domain.