The present utility model discloses a welding leakage current grounding device for a rotator. The device comprises a support, a carbon brush, an elastic component, a pressing plate, a bolt, a pad and a grounding conductor, one side of the support, which is close to the rotator, is provided with a carbon brush through hole, and one side of the support, which is close to the grounding conductor, is provided with a grounding through hole. the bolt can be used for fixing the support with the ground through the grounding conductor, the diameter of the carbon brush through hole is larger than that of the carbon brush, thus a gap is formed between the carbon brush and the support, and the carbon brush can move freely; on this premise, the carbon brush can be pressed on the rotary side of the rotator by the elastic component, the carbon brush can be reliably contacted with the rotary side, effective electric connection between the rotary side of the rotator and the grounding conductor can be finally ensured, conduction of the leakage current can be well realized, damages on gears, bearings and other parts inside a driving device of a rotating object caused by fire striking of the welding leakage current can be avoided, and service life of the driving device can be prolonged.