Aiming to explore the forming quality of Laser Cladding Ni45A, the response surface center composite design method was adopted to establish a mathematical model between the process parameters and the geometric characteristics of the cladding layer. The influence of laser power, scanning speed, and gas flow on the geometric characteristics was analyzed. Through the sensitivity analysis method, the sensitivity of the cladding layer′s geometric characteristics to the process parameters was obtained. Results show that increasing the laser power and reducing the scanning speed are beneficial to increase the height, width and the area of the cladding layer. Input energy in the molten pool is the main factor affecting the morphology of the cladding layer. In addition, sensitivity analysis shows that the geometric characteristics of the cladding layer are the most sensitive to the laser power. These research results provide a sensitive characteristic diagram for the geometric characteristics of laser cladding Ni45A, which provides a theoretical basis for further effective control of the forming quality of the cladding layer.