An optical lens comprises: a first lens having a negative focal power; a second lens; a third lens; a fourth lens; a fifth lens, wherein the fourth lens and the fifth lens forms an achromatic lens group; and a sixth lens, wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are sequentially disposed along a direction from an object side to an image side, wherein the first lens has at least one object surface facing the object side, and the object surface of the first lens is convex, and wherein the second lens has at least one image surface facing the image side, and the image surface of the second lens is convex so as to facilitate forming a concentric circle structure.