Abstract: Aiming at the technical difficulties of laser overlap welding of Al/Cu dissimilar metals, a new infrared-blue hybrid laser welding process was proposed. Laser welding of the overlap joints of 5052 aluminum alloy and T2 purple copper with thickness of 1 mm was carried out. The effects of different blue laser powers on the weld appearance, microstructure and mechanical properties of the joints were investigated. The results showed that the convection diffusion of copper elements from the lower copper plate to the upper aluminum plate can be weakened by using infrared-blue laser hybrid welding process with a blue laser power in the range of 0 ~ 500W. With the increase of blue laser power, the mixing degree of molten copper and aluminum was increased, resulting in more brittle Al-Cu intermetallic compounds (IMC) phases. Generates the following phases in the order from the copper side to the aluminum side, ϒ₂-Al₄Cu₉, AlCu, θ-Al₂Cu, α-Al + Al₂Cu eutectic structure and Al/Cu eutectic structure. Among these, Al₂Cu was the primary IMC phase at the interface layer of the joints. When the infrared laser power was 1050 W and the blue laser power is 300 W, the shear resistance of the joint reached up to 795.51 N. The joint was broken at the heat affected zone (HAZ) of the upper aluminum plate with a ductile fracture mode.