The invention discloses an LED (Light-Emitting Diode) optical lens for an automobile dipped headlight. The LED optical lens comprises an incident surface and an emergent surface, wherein the center of the bottom surface of the lens is provided with a cavity for accommodating an LED; the cavity wall of the cavity comprises a part of spherical surface, a part of cylindrical surface and a free curved surface on the top of the part of cylindrical surface to constitute the incident surface; the outer side face of the part of spherical surface and the outer side face of the part of cylindrical surface of the cavity refer to two different free curved surfaces; the top of the lens is a plane; and the top plane of the lens and the free curved surface on the outer side face of the part of cylindrical surface constitute the emergent surface. The lens has a small size, low veiling glare and high light energy utilization ratio, and is convenient to install; and light types and illumination distribution meeting the international GB25991-2010 light distribution requirement are generated.