The utility model discloses an SF6 online detection gas circuit for a plurality of electrical devices. The N devices carry out measurement in a time-sharing mode, gas in a pipeline is completely pumped back to the device to be measured after measurement of one device is completed, the phenomenon of gas mixing of the multiple devices is prevented, the buffer gas chamber is vacuumized after collection is completed, and then second-path collection is switched until the buffer gas chamber is vacuumized and externally arranged. The SF6 online detection device can be used for SF6 online detection ofa plurality of electrical devices, and ensures that SF6 gas of the plurality of electrical devices cannot be mixed in the monitoring chamber.