A novel electric field measurement safety warning system of live working based on micro-electromechanical system（ MEMS） sensitive structure chip is developed. The system can give out warning signal once the surrounding electric field value of a live working operator exceed the threshold. Based on phase sensitive detection principle

an analog demodulation circuit which can restrain background noise is designed. It achieves a faster response and gets a higher precision than digital processing circuit. A module of signal acquistion and wireless transmission is designed based on ARM microcontroller. Moreover

using Lab VIEW to display received data on upper PC. To reduce the impact caused by body sway

three-dimension measurement method is taken. Experimental result under 10kV lines has a good consistency with simulation result of ANSYS

and the early-warning error of safe distance is less than 4. 17 cm.