Abstract: Stable laser-MIG hybrid welding is the key to ensure the quality of welded joints, and it is crucial to control the stability of the welding process. The influence of the parameter variation of the rotating laser on the process stability of laser-MIG hybrid welding of TC4 titanium alloy welding wire was studied. High speed camera and NIDAQ data acquisition system were used to monitor arc parameters, droplet transfer and plasma behavior during welding. The results show that when the laser does not rotate, the arc parameters are unstable and the droplet transfer is dominated by large droplet transfer with obvious spatter and pores in the weld. When the laser rotates, with the increase of laser rotation frequency, the spatter and pores on the weld surface decrease significantly, and the droplet transfer changes from large droplet transfer to stable projected transfer. However, when the rotation frequency is low(25 Hz), there is a droplet deviation phenomenon during welding. When the rotation frequency is high(300 Hz), the arc parameters are unstable. When the rotation frequency is 150 Hz, the droplet deviation is eliminated, the welding process is stablest, the corresponding joint surface has excellent forming quality with small amount of pores and spatter.