Abstract: Human body electrostatic discharge is one of the main hazardous factors in the field of  electrostatic discharge protection engineering. According to the contact measurement for electrostatic potential，this paper puts forward a online monitor  system based on RS485 bus for human body electrostatic potential，develops one type of anti-static wrist strap and its fixture used in EPA（Electrostatic discharge Protection Area） operation，and designs the specialized measurement method for device and the whole system. The test results shows that the design realizes electrostatic continuous measurement，limit alarming and record traceability，and helps strengthen the ability of electrostatic protection and online measurement in aerospace industry workshop.

Key words: Electrostatic potential, Online monitor, Contact measurement, EPA, Traceability