High voltage circuit breaker SF6 gas parameter on -line monitoring device belongs to equipment monitoring technology field, including air inlet, gas vent, gas storage storehouse, antennal interface, power cord interface and inside monitor terminal, characterized by: inside monitor terminal includes microcontroller circuit, dew point sensor, pressure sensor, IV converting circuit and radio frequency module, dew point sensor and pressure sensor's signal output part all is connected with IV converting circuit, and IV converting circuit's signal output part and microcontroller circuit are connected, radio frequency module and antenna interface connection. The utility model discloses do benefit to high voltage circuit breaker's safe and reliable operation, can guarantee that high voltage circuit breaker SF6 gaseous density, humidity and temperature parameters carry out on -line monitoring's end system.