The multi-mode motion estimation algorithm of H.264 standard have the problems of complicated coding mode and much computing. Based on analysis of motion estimation algorithm from H.264-s reference model JM10, an original mode selecting algorithm using time or space relativity and an efficient matching rule linking with one-dimension sum of absolute difference (SAD) were designed. It optimized the former algorithm from mode selecting and coding speed by improving serial full searching motion estimation algorithm to parallel partial searching motion estimation algorithm and using one-dimension SAD matching rule combined with classical two-dimension SAD matching rule. The experiment results show that comparing with reference model JM10, the optimized algorithm makes coding rate increase 20%~30% but peak-value of signal to noise ratio (PSNR) just drop 0.03 dB and code speed just increase 1.5%. It means that this scheme increased coding speed with little quality fall of the reconstructed image.