H．264视频压缩标准采用多模式运动估计，可以有效减少块匹配预测误差，但随着模式选择的增多，算法计算量成倍增加。为此，提出一种带有中途停止的多层逐次消元运动估计算法(MSEHS)。该算法根据模式分布规律，使用多层逐次消元法加速大块模式的搜索过程，并且提出中途停止准则，判断是否继续进行小块模式的搜索。这样既保证了多模式运动估计的优点，又减少了冗余计算。实验结果表明，该算法比全搜索算法整体速度提高了近4倍，同时可以保持与全搜索算法非常接近的图像质量和比特率。

H.264 video coding standard uses motion estimation with multiple block sizes to reduce block-matching errors for higher rate-distortion performance. But the more modes are used, the more computation is needed linearly with the number of allowed block sizes. So a fast block motion estimation algorithm named multilevel successive elimination with half-stopping (MSEHS) is provided in this paper. According to the analysis of statistical characteristics about the best modes, multilevel successive elimination algorithm is described to speed up the searching process for the larger block modes firstly, then using the middle results SAD (sum of absolute difference) and motion vector, a half-stopping principle is defined as a threshold to judge whether it is necessary to continue the motion estimation for the smaller block modes. MSEHS algorithm not only reserves the advantage of multiple block modes in motion estimation but also deletes the redundant computation in the searching process. Experimental results show that the proposed technique provides competitive performance compared with full search algorithm, that is, highly reduced computational complexity, very similar image quality and bitrate.