The invention discloses a fast motion estimation method realized based on GPU (graphics processing unit) parallel. The method comprises the following steps: firstly, whether a current segment belongs to a background domain is judged through a maximum probability using local full-search; secondly, if the current segment belongs to the background domain, full-pixel precision search is ended, or else a search step length is increased by reducing a search domain resolution, and an optimal motion vector distribution range is captured by executing local full-pixel full-search of low resolution, i.e., coarse positioning; thirdly, after the segment belonging to the motion domain is subjected to coarse positioning, the motion vector distribution range is refined by local full-search, so as to accomplish motion estimation of full-pixel precision, i.e., refining positioning; finally, a search template with high density and high precision is used for refining the motion vector, thereby accomplishing a quarter of pixel precision search and ending the motion estimation of the current segment. A termination judgment technique is adopted in the search process, i.e., if a minimum distortion reference segment reaches a set matching precision, the full-pixel search process of the algorithm is ended, and all search points of each step in the search process will have no change.