Online monitoring device for insulating joint of long oil and gas transmission pipeline

The utility model relates to an on-line monitoring device for an insulated joint of a long oil and gas pipeline, which comprises an explosion-proof box body, and a power supply module, a host module and a lightning protection module are arranged in the explosion-proof box body. Two ends of the host module are respectively connected with the output ends of the power supply module and the lightning protection module, and one end connected with the power supply module is also provided with a debugging port; the input end of the lightning protection module is respectively connected with an oil and gas pipeline in-station lead, an oil and gas pipeline out-station lead, a reference electrode, a natural test piece, a current test piece and a power-off test piece which are buried underground; the oil-gas pipeline in-station lead is connected with the in-station pipeline, and the oil-gas pipeline out-station lead is connected with the out-station pipeline; and the reference electrode, the natural test piece, the curre