The utility model relates to a power system fault detection technical field, concretely relates to monitoring devices of transmission line discharge performance trouble based on magnetic field suddenchange, including the host computer, the upper portion of host computer sets up the stay tube, and the upper end of stay tube sets up the photovoltaic board, and the inside of host computer sets up the magnetic field sensor, shoots starting circuit, shoots device, memory and signal transmitter and power supply system, the utility model discloses can the automatic acquisition transmission line trouble picture information of electric arc burning constantly when discharging, have or not electric arc combustion phenomena constantly in the trouble through the circuit parts in the assay picture covering power, judge the concrete position of circuit body trouble, avoided that transmission line makes an inspection tour a series of problems of bringing after the accident, improved fault line's tourefficiency, the quick analysis processes that is favorable to the trouble with the power supply recovers, improve electric wire netting safety operating level.