To solve the problem of low absorption and welding surface collapse in the laser welding of the 6061 aluminum alloy, the powder was first added to the surface of the weld by laser cladding. The effect of laser cladding powder type on the microstructure and hardness of the 6061 aluminum alloy was studied. The results show that laser cladding of single Al powder, Si powder, and Ni powder can all improve laser absorption during laser welding of aluminum alloy, but each material has specific limitations, such as reducing the number of strong phases, generating other phases, and the nonevening of phases. Two kinds of mixed powder, Al:Si and Al:Ni, can overcome these limitations to a certain extent. Laser cladding with three kinds of mixed powder resulted in a better welding effect than when using two kinds of mixed powder or a single powder. By applying an extreme vertices design, the optimum ratio of Al-Si-Ni powder was determined as 0.737:0.185:0.078, resulting in the uniform microstructure of the weld without delamination. The mechanical properties test shows that the hardness of the laser cladding with powder was better than that without laser cladding powder, and the tensile strength of the weld was 83% of the base material.