The invention relates to a device and a method for testing influence of different metal materials on SF6 local sudden discharge fault decomposing. The device comprises a pressurizing system, an SF6 discharging gas chamber, a detection system and a metal material protrusion defect model, wherein the output end of the pressurizing system is connected with the metal material protrusion defect model; the metal material protrusion defect model is arranged in the discharging gas chamber, and the detection system is simultaneously connected with the discharging gas chamber and the pressurizing system. The device and the method have the beneficial effects that the cost is low, and the testing method is simple and is suitable for being popularized; the spark discharge fault state caused by different metal protrusion defects in the SF6 electrical insulation equipment can be well simulated; the blank of failure to evaluate the influence of different metal materials on SF6 spark discharging decomposing in the existing test equipment and method for detecting the SF6 decomposing gas component to evaluate the SF6 insulation electrical equipment state is filled; the possibility is created for verifying the influence characteristic and action mechanism of the metal materials on the SF6 spark discharging decomposing.