In welding process, the flow characteristics of molten pool are closely related to the defects such as porosity, undercut and so on. It also has important influence on the crystallization process of molten pool and weld formation. The research objects of low-alloy high-strength steel are drilled holes and then filled with ZrO2 particles as tracer particles. And the position of keyhole, arc shape and flow characteristics of molten pool are recorded by high speed camera. The flow law of the molten pool surface during laser-GMAW hybrid welding is studied at different laser-arc distances. The results show that when the laser-arc distance is 1 mm, the keyhole is unstable and drift occurs. At the same time, the tracer particle flows to the rear along the central axis after circumventing the arc action zone. When the laser-arc distance is 3 mm, the position of the keyhole is relatively stable. However, the typical Karman vortex phenomenon appears during the flow of tracer particles. When the laser-arc distance is 5 mm, the keyhole position is stable, while the stagnation phenomenon of tracer particles appears as it flows through the middle region of laser keyhole and arc action zone. Under this condition, the moving distance of tracer particles is the largest. Comparing the cross-section morphology of the joints at three kinds of laser-arc distances, we can find that when the laser-arc distance is 1 mm, there are some pores at the bottom of the weld, which is caused by the unstable keyhole because of the small laser-arc distance. When the laser-arc distance is 5 mm, the distance between the two heat sources is too large, resulting in the increase of the coupling efficiency of the two heat sources, and significant decrease of the penetration depth. When the laser-arc distance is 3mm, the weld has no defect and the penetration depth is the largest.