The effect of fiber laser on MIG arc was investigated with 8 mm 7075-T6 high strength aluminum alloy as base material. The arc shape, droplet transfer form and electrical signal in the process of MIG welding and laser-MIG hybrid welding were analyzed. The stability of the hybrid welding process was evaluated by standard deviation analysis. The results show that with the increase of laser power, a large number of laser-induced plasma enters the arc column area, providing more conductive channels, which makes the heat of MIG arc more concentrated and the short circuit transition disappear. Due to the continuous effect of laser, the keyhole becomes a continuous electron emis-sion source, and a stable cathode spot will be formed near the keyhole, which enhances the stability of MIG arc at the base current state. By using the method of standard deviation analysis, the voltage standard deviation of single MIG welding arc and laser-MIG hybrid arc within 4 seconds was calculated. The standard deviation of single MIG arc voltage was 1.05, and the standard deviation of MIG arc voltage in laser-MIG hybrid welding was 0.71–0.86, so the hybrid welding process was more stable.