The embodiment of the invention discloses a testing and calibrating method and device of recharge rate of an online detector of sulfur hexafluoride. Through measurement of standard gas chamber pressures before and after recharging sample gases to the online detector of sulfur hexafluoride to be inspected, the recharge rate of the online detector of sulfur hexafluoride to be inspected is calculated, which achieves test and calibration of recharge rate of an online detector of decomposition product of recharge-type sulfur hexafluoride electrical equipment. The calibrating method has strong automation ability and simple operation, and provides a good basis for the safe and stable operation of the online detector of sulfur hexafluoride.