The present invention discloses an iris lens. The iris lens has a total effective focal length f, the iris lens comprises from an object side to an imaging surface in order along the optical axis: a first lens, a second lens and a third lens. The first lens has a positive focal power, and the object side surface is a convex surface; and the second lens and the third lens both have the positive focal power or negative focal power. The distance TTL of the object side surface and the imaging surface of the first lens on the optical axis and the total effective focal length f satisfy the 0.7