Abstract: The 30CrNi2MoVA steel is commonly utilized in the manufacturing of military gun barrels. However, the harsh working conditions that these barrels are exposed to cause wear, cracks, and other types of damage to the surfaces of the steel parts. As a result, the laser melting deposition technology (LMD) is frequently implemented to repair these surfaces. The quality and mechanical properties of the parts are significantly influenced by the thermal behavior that occurs during the LMD process, as it affects the material structure evolution. To investigate these effects, a finite element model of the temperature field of 30CrNi2MoVA steel during the LMD process was developed using ABAQUS. This model was utilized to examine the temperature distribution law during the LMD process, and the influence of processing parameters on temperature field.The thermal history and heat transfer characteristics of thin-walled parts during deposition were analyzed, and relevant experiments were designed to verify the applicability of the model.The study revealed that the LMD temperature field has a comet-shaped pattern, and for every 100 W increase in laser power, the maximum temperature of the molten pool increases by about 40 ℃, while the scanning speed has an opposite effect. Moreover, as the deposition layers increase, the thermal accumulation effect intensifies, resulting in an increase in the peak temperature of the molten pool and a decrease in cooling rate.