Abstract: In order to study the forming mechanism of molten pool and heat-affected zone in the preparation of amorphous alloys by laser additive manufacturing, finite element software ANSYS was used. The thermal effect of laser rapid melting Zr₆₅Al_7.5Ni₁₀Cu_17.5 amorphous alloy was numerically simulated and analyzed. The simulation results show that, average cooling rate of molten pool is 6.3×10⁴K/s when laser solidification is carried out at single point. Average cooling rate in heat affected zone is 1.4×10⁴K/s, much higher than 1.5K/s of critical cooling rate of Zr₆₅Al_7.5Ni₁₀Cu_17.5 amorphous alloy. The thermal change of single-point laser melting meets the growth conditions of amorphous alloys. In the process of single-channel laser melting, average cooling rate of molten pool is 2.11×10²K/s, still relatively high. However, average cooling rate of heat affected zone is 74K/s and low. In addition, relaxation accumulation occurs in the heat-affected zone. It may cause a certain degree of crystallization. This study provides theoretical basis for thermal effect of amorphous alloys prepared by laser additive manufacturing.