The velocity distribution in the molten pool has a significant impact on the cladding depth and width of the laser cladding layer and the surface morphology, which in turn affects the quality of the cladding layer. To this end, a thermal-fluid coupling model of laser cladding is constructed, and the cladding process under different laser power and powder feed rate is simulated by using it. Therefore, this paper uses this model to deeply study the effect of laser process parameters on the temperature field and the velocity field in the molten pool. It was found that as the laser power increases, the spot size or the scanning speed decreases, the peak value of the fluid flow velocity in the molten pool increases during the rising period, and the decline in the peak period of the flow velocity decreases gradually or even stabilizes. while the change of the powder feed rate has almost no effect on the velocity field. In addition, the influence of the surface tension coefficient on the velocity field in the molten pool is also studied.For the cladding material with negative surface tension coefficient, It was found that the fluid in the molten pool flows from the laser irradiation area to both sides, which makes the molten pool shallower and deeper.The cladding material containing active elements such as S has a positive surface tension coefficient, and the fluid in the molten pool flows from both sides of the molten pool to the middle, which makes the molten pool deeper and narrower. As the absolute value of the surface coefficient increases, the fluid velocity peaks will increase with it.