In order to reduce the risk of electric shock to distribution maintenance staff, it is necessary to develop a portable device for the power-frequency electric field measurement. In the article, the principle and realized method of a wearable gauge for the power-frequency electric field is introduced. The performance of the device is also verified through the test. The device can issue a sound light alarm , reminding distribution maintenance staff not to forget the electrical inspection process when they approach the charged body. The device"s use can improve the present situation of visual inspection of safety distance and effectively improve the safety awareness and level of carriers.