H.264 KTA increases the coding performance at the cost of high computational complexity.Its adoption of adaptive interpolation filter（AIF）and 1/8 pixel MV resolution causes that fractional pixel motion estimation（FPME）exerts more significant influence on the computational complexity of video coding.In this paper，we propose an algorithm to speedup FPME by using uni-model characteristics and the MV correlation of fractional pixel motion compensation.According to experiments，our algorithm achieves much higher speed than other fast FPME algorithms with neglectable R-D lost compared with F帧/s algorithm.