One of the surface modification methods is proposed in this report to improve the wear resistance of light metal such as aluminum alloys. At first alumite layer is formed on the surface of aluminum alloy JIS A6061 which was used as the substrate with anodic oxidation treatment method. Then thin layer of CrN is coated with sputtering method, and diamond like carbon (DLC) layer is finally coated with ion plating method. The influence of the thickness of the alumite layer on wear-resistance is experimentally investigated. The critical load of the coated aluminum alloy in scratch test is measured with the surface property tester, and the wear amount of the coated aluminum alloy is measured with the SUGA abrasion tester. The main results obtained are as follows: (1) The critical load of coated aluminum alloy with the alumite layer in the scratch test is higher than that without the alumite layer. (2) The wear amount of the coated aluminum alloy increased with the increase of the thickness of the alumite layer. (3) This combined surface treatment method can become new surface modification method because this method provided excellent adhesive strength and good wear-resistance.