The invention discloses an operation calibrating method for a SF6 electrical equipment insulation state on-line monitoring system. A standby calibrating port is used for calibrating the on-line monitoring system and it is provided that a least square method is used for calibrating the operating on-line monitoring system so as to reduce errors caused by a sensor used for a long time as much as possible and to guarantee the reliability of the subsequent continuous operation of the system. The operation calibrating method is suitable for a SO2 content and purity on-line monitoring system for an operating SF6 electrical equipment current transformer and circuit breaker, an on-line monitoring system capable of simultaneously monitoring moisture, SO2 content and purity, a GIS photoacoustic spectrometry decomposition component online monitoring system, and a SF6 leakage distributed on-line monitoring system to overcome the shortcomings in the prior art.