The property of H.264/AVC CAVLC(context-adaptive variable-length coding) and the characteristic of Huffman Coding are analyzed, and a high efficiency implement algorithm of CAVLC decoding based on codeword classification mapping is proposed in this paper. According to the characteristic of Huffman Coding, mapping the codewords and it's syntax element to classification mapped tables, accelerate the process of CAVLC decoding enormously at the expense of little memory consumption. The simulation results show that the proposed algorithm achieves an approximate 24-50% speed advance without degrading video quality as compared to the conventional CAVLC decoding.