The study aimed to examine the relationship between the process parameters of the high-temperature nickel-based alloy additive manufacturing process and the cladding morphology and quality. First, an Inconel718 laser cladding model was established on the surface of 45^# steel by using ANSYS analysis software, APDL programming, and life and death unit technology. By comparing the size of the molten pool obtained by numerical simulation and experimental results, the accuracy of the model was verified to reduce subsequent test cost. Second, taking the quality of the cladding layer (forming coefficient) as the index, a regression equation was established by using the regression orthogonal experimental design, and the order of influence of the process parameters on the quality of the cladding layer was studied, followed by laser power, powder feeding rate, and scanning speed. Our results showed insignificant effect of the interaction on the quality of the cladding layer. However, the laser power and powder feeding rate exhibited the most significant impact on the quality of the cladding layer. Therefore, a single factor test is designed to analyze the influence of laser power and powder feeding on the hardness, dilution rate, and cladding morphology of the cladding layer. Through the analysis of variance, the optimal solution to the test is predicted to be as follows: laser power 1200 W, scanning speed 23 mm/s, powder feeding rate 20 g/min. These findings are consistent with the results obtained in the experiment. Moreover, the optimal parameters are verified by multi-pass lap experiments , and the structure is dense and fine. The cladding layer was found to have a good metallurgical bond with the substrate, which has a certain guiding effect on the follow-up practical production work.