In order to provide intelligent detection and auxiliary debugging means for bridge equipment electric control system, a debugging diagnostic instrument is designed and developed based on Qt. The overall design scheme of the system is introduced, and the software and hardware design and functional interface planning are described respectively. The data communication with the electric control system based on CAN bus protocol is carried out to monitor and record the working status of the bridge mechanism and the sensor detection signal in real time. The results show that the debugging diagnosis instrument has the functions of fault diagnosis, erection guide and data calibration, and has friendly human-computer interaction, convenient operation and high application value.