Light trapping structure can increase the absorption of incident light. In this paper, we make used of porous anodic aluminum oxide as mask to fabricate the light trapping structure on the glass substrate before AZO film deposition. The average size of the pit is about 2 and 1μm, respectively. It was found that the efficiency of the n-i-p solar cells using AZO film with pit arrays as back surface reflectors have obvious improvement. Furthermore, we improved the external quantum efficiency of the solar cells in the infrared region.