Abstract: In order to improve the color difference after aluminum alloy welding repair and improve the aesthetics of the repaired product, the mechanism of the color difference of ZL101A aluminum alloy generated by TIG welding was analyzed.The effects of the roughness, metallographic structure on color difference were studied. The results show that with the surface roughness decreasing, the welding color difference first increases and then decreases; the precipitation of the black Si phase in the metallographic structure increases the color difference, while the color difference is relatively small when the gray phase Mg₂Si is precipitated, but with the coarseness and denseness of Mg₂Si, the color difference increases.