In view of the current symbol sequence encoding having the problem of slow encoding speed , this paper proposes an algorithm to improve the encoding speed by reducing the average search length .According to the sym-bol probability , it designs three coding algorithm that are a sequential search , big probability priority first search and small probability priority first search .Through the analysis and comparison of the average search length of the three coding algorithm , teh results show that the average search length is the shortest for the big probability priority search algorithm .Accordi...