Abstract: The process of laser processing of metallic materials involves complex physical phenomena, and its internal mechanism covers multiple disciplines and fields. In this study, based on the Level Set method, a numerical model of the molten pool formed by laser processing of TC4 titanium alloy was constructed in the finite element simulation software, and the dynamic behavior of temperature field, velocity field and metal phase transition was systematically explored. The model uses the Level Set method to accurately trace the gas/liquid phase transition interface, and uses the enthalpy-pore method to treat the liquid/solid mixed paste region, so as to achieve high-precision numerical simulation in the finite element simulation software. The influence of laser parameters (power, spot radius) on the temperature field, velocity field and phase transformation behavior of the melt pool is revealed. The results show that the high power density and small spot radius can significantly increase the flow rate and temperature of the molten pool, accelerate the phase transformation process of the material, but may also lead to liquid splashing and increased surface roughness. These results provide an important theoretical basis for optimizing laser processing process parameters and improving processing quality.