In accordance with the complexity of AVS motion search and block mode selection algorithm, the paper poses a AVS quick mode selection algorithm based on premature termination norm and adaptive threshold. The algorithm can avoid much cost calculation of the useless macro block and save a lot of time on moving search and block mode selection in encoding process. Experimental results show that the computational capacity saved by the algorithm can amount to 78.6% at most, and the dropped level of Bits is larger than PSNR. The encoding speed can be effectively increased without the lower encoding performance.