This paper reports a novel process for fabrication of polymer concave lens arrays with different focal length. The process involves a hot embossing process with a polymer substrate and a small steel ball array. Only one embossing step is required, which a concave lens array pattern is directly fabricated onto a polymer substrate. In addition, the diameter and shape of the polymer concave lens array can be changed and controlled by adjusting the processing conditions of the hot embossing process. Thus, polymer concave lens arrays with different focal length can be fabricated. The experimental results evidence that the proposed method can fabricate various polymer concave lens array devices with high productivity and low cost.