This invention provides an optical image lens system comprising: a positive first lens element having a convex object-side surface; a second lens element; a positive third lens element; a fourth lens element; a positive plastic fifth lens element having a convex object-side surface and a concave image-side surface, at least one of the object-side and image-side surfaces is aspheric; and a negative plastic sixth lens element having a concave image-side surface, at least one of the object-side and image-side surfaces is aspheric, wherein the shape of the image-side surface changes from concave at the paraxial region thereof to convex while away from the paraxial region thereof.