Metal parts with textured bumps are widely used in engineering, and controlling their morphology precisely is critical to control the performance of related parts accurately. In this paper, the 45 steel is taken as the research object, and a two-dimensional axisymmetric model is used to simulate to explore the evolution of the temperature field and the direction and velocity of fluid flow in the molten pool irradiated by the pulsed laser. Therefore, the microscopic mechanism and dynamic process of the formation of the textured morphology can be studied. The results show that during the heating period and while the temperature of the surface is below the critical temperature, the tangential stress is negative, and the melt flows to the center of the molten pool. If the surface temperature is above the critical temperature, the tangential stress is positive, and the melt flows to the edge of the molten pool, finally forming a convection-free location at the junction of the two circulations. For the same circulation, the greater the tangential stress is, the greater the peak velocity is. If the new circulation velocity is small when the surface temperature exceeds the critical temperature, it will weaken the deformation of the morphology at the last moment. Otherwise, an abnormal shape will be produced at the convection-free position.