An optical leveling module (1) includes a sensitive element (10) with a plurality of sensitive areas (11) thereon, and an optical leveling layer (20) mounted on the sensitive element and including a plurality of lenslets (21) wherein a refractive index of the lenslets progressively increases from a center of the optical leveling layer to a periphery of the optical leveling layer. The optical leveling module further includes an adjusting lens (30) and a filter (40) above the optical leveling layer. The intensity of image is essentially uniform after being adjusted by the optical leveling module. A method for manufacturing an optical leveling layer of the optical leveling module is provided. At first, enhance an optically resistant block's refractive index by doping. Second, cut it into slices. Third, each slice is etched to form a plurality of columns. Finally, each column is fused to form a lenslet.