An optical image collecting system includes, in order from an object side to an image side, a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element and a sixth lens element. The first lens element with positive refractive power has a convex object-side surface. The second through sixth lens elements all have refractive power. The fifth lens element has a concave object-side surface and a convex image-side surface, wherein at least one of the object-side surface and the image-side surface of the fifth lens element is aspheric. The sixth lens element has a concave image-side surface at a paraxial region, wherein the image-side surface of the sixth lens element changes from concave at the paraxial region to convex at a peripheral region, and both of an object-side surface and the image-side surface of the sixth lens element are aspheric.