The invention discloses a fault diagnosis tester of an electric submersible pump working condition monitor system. The fault diagnosis tester comprises a digital voltmeter, an anti-explosion machine box, a liquid crystal displayer, a power indicator light, a state indicator light, a switch, a digital ammeter, an inductor, control circuit boards, a power module, a lithium battery pack, a power interface, a testing connector and a USB communication interface. The digital voltmeter and the digital ammeter are arranged on the left side of a front panel of the anti-explosion machine box. The liquid crystal displayer is arranged in the middle of the front panel of the anti-explosion machine box. The power indicator light and the state indicator light are arranged on the right side of the front panel of the anti-explosion machine box. The fault diagnosis tester can be fully utilized for carrying out fault detection fast on the use spot of a pump working condition monitor, faults are treated in time, the time of pump shutdown for oil extraction can be shortened so that the yield loss caused by pump shutdown for maintenance can be reduced, and cost is indirectly reduced; and the fault diagnosis tester is used for carrying out fault detection on the working condition of a pump, and therefore the maintenance utilization rate of the fault diagnosis tester can be effectively increased.