An optical lens system for taking image comprises, in order from an object side to an image side: a first lens element with positive refractive power having an aspheric convex object-side surface and an aspheric concave image-side surface; a second lens element with positive refractive power having an aspheric convex object-side surface and an aspheric concave image-side surface. Radii of curvature of the object-side surface of the first lens element, the object-side and image-side surfaces of the second lens element are R1, R3 and R4 respectively, focal lengths of the optical lens system for taking image, the first and second lens elements are f, f1, f2 respectively, an on-axis distance between the first and second lens elements is T12, a center thickness of the second lens element is CT2, they satisfy the relations: 0.76 mm−1 1.0.