An optical lens device for a head-mounted display includes a transparent support substrate and a Fresnel lens disposed thereon. The Fresnel lens includes a central lens element and a plurality of prismatic elements arranged relative to the central lens element in a proximal-to-distal manner. Each of the prismatic elements has a base facing toward the support substrate, and a draft facet and a sloped facet extending from the base away from the support substrate to intersect with each other to form an apex. Each of the prismatic elements has a height measured from the base to the apex and not greater than 75 μm. The base has a width not greater than 250 μm. A method and a mold for producing the optical lens device are also disclosed.