The invention provides an optical lens, which comprises four lenses with focal power and sequentially comprises a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with positive focal power and a sixth lens with negative focal power from an object side to an imaging surface along an
optical axis, the second lens has positive focal power, the object side surface of the second lens near the
optical axis is a convex surface, and the image side surface of the second lens is a convex surface; the third lens has positive focal power, the object side surface of the third lens is a
concave surface near the
optical axis, and the image side surface of the third lens is a convex surface near the optical axis; the fourth lens has negative focal power, the object side surface of the fourth lens is a
concave surface near the optical axis, and the image side surface of the fourth lens is a convex surface near the optical axis; wherein the
real image height IH corresponding to the maximum
field angle of the optical lens and the effective
focal length f of the optical lens meet the following conditions: 1.3 lt; iH / flt; 1.6); the curvature
radius R7 of the object side surface of the fourth lens and the curvature
radius R8 of the image side surface of the fourth lens meet the following formula:-0.45 lt; (R7-R8) / (R7 + R8) lt; and-0.2%. According to the optical lens provided by the invention, the overall aberration of the optical lens can be reasonably corrected, and the
imaging quality of the optical lens is improved.