Abstract: According to the disorderly arrangement of the connecting wire box of transformer test instrument, the problems of transformer test preparation and finishing time caused by finding and arranging wires are systematically analyzed, and an intelligent transformer test junction box is developed. The core control circuit of test junction box is designed based on STC89C52 single chip microcontroller, taking Hall switch as the open-box trigger unit, making the control panel according to the functional requirements, and installing the fixed slot matched with the connection line. The test junction box has various functions such as classified placement, fixed equipment, automatic detection, visual identification and so on. After the use of the test junction box, the transformer test preparation and closing time is shortened from 69 min to 37.2 min, saving an average of 31.8 min, which effectively avoiding related electrical safety accidents, and improving the working efficiency of testers.