Owing to the great computation complexity of the ME (motion estimation) in video coding, a lot of fast ME algorithms have been proposed in literature. Most of them are designed based on a given hypothesis about the character of the video’s motion field. But due to the inherent variety of the real-world video, these algorithms are not generally efficient, especially for the variable block size ME in H. 264, only using one single ME strategy is difficult to get satisfactory result. This paper firstly will give two different fast ME algorithms, which aim at video sequences with different character. An adaptive strategy is proposed to combine the two algorithms together for H. 264. Experimental result shows that this strategy can keep coding efficiency in all kinds of video sequences, meanwhile the computation complexity is reduced adaptively according to the video’s content.