The present invention provides an optical lens system comprising, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fourth lens element; and a fifth lens element having a concave image-side surface, the object-side and image-side surfaces thereof being aspheric and at least one inflection point being formed on the image-side surface. Such arrangement of optical elements can effectively minimize the size of the optical lens system, lower the sensitivity of the optical system, and obtain higher image resolution.