Power transformer is the hub of power transmission in power network. Routine state maintenance test is an important link in the operation and maintenance of power equipment, and it is one of the effective means to ensure the safe operation of power system. In this paper, a transformer test adapter box is designed to be used in the current routine test of transformer status maintenance in substation, which needs to be climbed many times in high altitude operation. This innovative method can realize the test wiring of changing working surface. The staff only need to complete the wiring and disconnection work once on the transformer. This reduces the potential safety hazards caused by climbing transformers in several high-altitude operations, shortens the test time and improves the work efficiency. An example shows that this method has high accuracy and reliability. The application of this result has great economic and social benefits in saving human resources costs, enhancing the accuracy of test data, saving time costs, reducing planned power outage losses, reducing equipment losses, strengthening the security of power network operation, and improving the quality of operation and maintenance management.