This invention provides an optical lens system comprising: a first lens element with positive refractive power; a second lens element with negative refractive power; a third lens element with negative refractive power having a concave object-side surface and at least one of the object-side surface and the image-side surface thereof being aspheric; a plastic fourth lens element having at least one of the object-side surface and the image-side surface thereof being aspheric; a plastic fifth lens element having a concave image-side surface, at least one of the object-side surface and the image-side surface thereof being aspheric, and at least one inflection point is formed on at least one of the object-side surface and the image-side surface thereof. By such arrangement, photosensitivity and total track length of the system can be reduced, and the aberration and astigmatism of the system can be effectively corrected. Moreover, high image resolution can be obtained.