The paper optimizes AVS key coding algorithm, and designs high coding efficiency and high coding quality AVS encoder XAVS based on x86 platform. The coding system supports a variety of search options, scene change detection, rate distortion optimization (RDO) and rate control algorithms. The experiment results show that subjective quality of XAVS is better than that of rm52j; In the case of the same objective quality, the output bit rate of XAVS is lower than the rm52j about 5% and Encoding speed of XAVS is 4-7 times that of rm52j.