Motion estimation is a very important part in the inter prediction technical of video coding

and the performance of a video coder largely depends on the efficiency and precision of motion estimation. The full search algorithm is seldom adopted because of its enormous complexity of computation

and now the fast algorithms of motion estimation such as three step algorithm and cross search algorithm are used widely. But the matching precision of these algorithms is low and in some cases they can not produce a good result. This paper first discusses the spatial correlation and time continuity of the motion object in video coding. Then

a new fast motion estimation algorithm based on the spatial correlation and time continuity of the motion object is presented. The average search times for computing motion vectors per macroblock of this algorithm are less than those of the three step algorithm and the matching precision of this algorithm is very close to that of the full search algorithm by experiments. Moreover

the output bits of the coder using this algorithm are less than those of the coder using the full search algorithm.