As the intelligent of substation is continuously improved, the power equipment is updated fast. The security risk of substation maintenance is gradually increasing. Under the background, a smart bracelet for the maintenance work of substations is designed to reduce the security risk in the maintenance work. The main functions of bracelet are heart rate monitoring, exercise detection and near-electricity alarm. Firstly, the overall function of the wearable bracelet is designed and involved key technologies are briefly summarized. Then, the chip selection, debugging and software flow design of the key functional modules such as the main control chip of the bracelet, the heart rate detection module, the fall detection module, and the near power alarm module are completed. In the end, the hand ring is tesed to verify the practicability of each function. The wearable device can improve the security of maintenance operations and the intelligence of substation safety monitoring system.