This invention provides a photographing lens system comprising, in order from an object side to an image side: a first lens with positive refractive power having a convex object-side surface; a second lens with negative refractive power, both its two surfaces being aspheric; a third lens having a concave image-side surface, both its two surfaces being aspheric and at least one of them having at least one inflection point; and an aperture stop disposed between an imaged object and the first lens; wherein there are only three lenses with refractive power; the focal length of the photographing lens system is f, the focal length of the first lens and the second lens is f1 and f2, respectively, the radius of curvature of the object-side surface of the first lens is R1, the Abbe number of the first lens and second lens is V1 and V2, respectively, and they satisfy the relations: 1.28