The stability of the welding process is an important factor determining the quality of the weld seam, and the welding spatter and weld surface morphology are direct manifestations of the stability of the welding process. In order to obtain a stable aluminum alloy laser–arc hybrid welding (LAHW) process, this study used high-speed photography to count the number of welding spatters and analyze the weld surface forming quality. A comprehensive qualitative evaluation of the stability of the welding process was carried out. Combined with the fundamental principles of laser welding and arc welding, the mechanism of reducing spatter and stabilizing the welding process is discussed. Under the present experiment condition, the welding spatter could be reduced by appropriately increasing the Ar shielding gas flow, arc length, distance between the center of laser beam and wire tip or decreasing the electromagnetic contraction force of the arc. The LAHW spatter suppression mechanisms are that: Firstly, the preheat effect of laser enlarges front welding pool which stabilizes metal transfer; Secondly, the optimized processing keeps reasonable force of arc on molten drop. The stable LAHW process contributes to the success of industrial application.