The present invention relates to a telecentric F-theta optical lens and an optical system; the optical lens comprises a first lens, a second lens, a third lens and a four lens, which are arranged in sequence along an incidence direction; the first lens is a double concave negative lens; the second lens is meniscus positive lens with a curved surface toward the incidence side; the third lens is a plane convex positive lens or a double convex positive lens; the fourth lens is a convex plate positive lens or a double convex positive lens. Besides, preferably the optical power of each lens and the system optical power of the optical lens satisfy that: f1/fw is more than -0.65 and less than -0.55, f2/fw is more than 1.6 and less than 2.5, f3/fw is more than 0.8 and less than 1.2, f4/fw is more than 2.2 and less than2.5, wherein, f1, f2, f3 and f4 are the optical powers of the first lens, the second lens, the third lens and the fourth lens respectively; fw is the system optical power of the optical lens; by arranging the four lenses to be a 'negative-positive-positive-positive' separated optical power system, the exit pupil position of the F-theta optical lens is positioned at an afocal position, and the image main light in the field of view is parallel mutually and perpendicular to the imaging surface. Besides, the astigmatism and the field curvature of the system are regulated perfectly, the imaging on the whole field of view is uniform, and no vignetting exists.