Abstract: Welding dissimilar metals between stainless steel and copper alloys combines the high electrical and thermal conductivity of copper with the superior corrosion resistance, high strength, and low cost of stainless steel, thereby leveraging the advantages of both materials. However, in laser welding of stainless steel and copper alloy plates, the significant differences in their physical properties often result in low joint strength. This study investigates the use of stainless steel filler wire and the adjustment of welding parameters for laser lap welding of 304 stainless steel and commercially pure copper ( copper) plates. The tensile strength, hardness, and microstructure of the welded joints were evaluated. Results indicate that different welding parameters significantly affect the performance of the joint. When the laser power is 750 W and the welding speed is 100 cm/min, the tensile strength and hardness of the joint are markedly improved. The joint achieves a maximum lap-shear strength of 165.8 MPa and a peak hardness of 126.4 HV. This demonstrates that appropriate adjustment of parameters, such as laser power and welding speed, can effectively control joint properties. This research provides a theoretical basis for the application of laser welding of stainless steel and copper.