Abstract: Plume is an inherent physical phenomenon in the process of fiber laser deep penetration welding. The plume consisted of two parts: the oscillating part at the bottom and has a serious negative impact on the laser welding process. At present, the removal method of narrow and long plume is mainly horizontal blowing with supersonic air curtain, but there is no targeted removal method for the swing part at the bottom. In this paper, 6 kW fiber laser is used to weld low carbon steel, and the influence of side shaft high-speed protective air flow on these two parts of plume is compared and studied. At the same time, the influence of protective airflow direction on the welding process was studied, the welding process was observed and the weld morphology was analyzed.