Abstract: In order to reveal the evolution mechanism of pores in the Laser Wire Additive Manufacturing (LWSM) process and achieve effective regulation of pore defects, a numerical model of stomatal evolution was established in this study, the effect of laser power on porosity evolution during laser fuse additive manufacturing was systematically analyzed, further explored the pore escape mechanism. The results show: As the laser power increases, the velocity field inside the molten pool is enhanced, forming a "vortex", this prevents bubbles from escaping the molten pool, eventually pores are formed in the deposited layer. The bubbles in the molten pool are mainly affected by buoyancy, thrust generated by the flow of the molten pool, viscosity of the liquid metal and gravity. The thrust generated by the molten pool flow has different effects at different stages of bubble escape, Gravity and viscous drag act as hindering forces, while buoyancy and molten pool flow generate an upward thrust to promote the escape of bubbles from the molten pool. The research results provide a theoretical basis for optimizing process parameters and reducing porosity defects in laser fuse additive manufacturing.