This invention provides an optical image-capturing lens assembly comprising, in order from an object side to an image side: a first lens element with positive refractive power; a second lens element with negative refractive power; a third lens element, the object-side and image-side surfaces thereof being aspheric; and a fourth 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 at least one of the object-side and image-side surfaces thereof. The present lens assembly is further provided with a stop and an electronic sensor for image formation of an object. The stop is disposed between the object and the second lens element, and the electronic sensor is disposed at an image plane.