A flexible polymer is considered as an alternative of low-cost mold materials. Molds with a high density aspect ratio, smooth surface, vertical sidewalls and lightweight have been fabricated and it is easy-to-use features in the hot embossing process. The study also indicated that the flexible metal/polymer mold could be used for thermoplastic polymer patterning with high fidelity and low cost. Using the flexible metal/polymer mold, 10um and 5um structures were fabricated.