Thin strip with varying thickness, a novel structural and functional material, is fabricated by micro flexible rolling, and has three thickness features including the thicker zone, the thinner zone and the transition zone. Rolling and roll lifting speeds determine the thickness distributions, and have a great influence on the surface roughness, then the final product quality which is of significant importance for thin materials in subsequent processing. In this study, surface roughness alteration of aluminium alloy strips during micro flexible rolling was investigated with considering the influences of rolling speeds, roll lifting speeds, thickness ratios (the ratio of the thicker zone to the thinner zone) and lubrication conditions, and the mechanisms were discussed. The results show that rolling parameters have a significant effect on the alteration of surface roughness from the thicker zone to the thinner zone along the rolling direction. The experimental observations indicate that the surface roughness of thin strips with varying thicknesses presents a decreasing tendency with the increase of contact area results from downward rolling phase along the transition zone, however, it is constantly higher than that in the upward rolling phase.