Objective: Studies on extraction and purification technology of the Chinese medicine leeches

preparing process of extracting leeches to provide technical basis. Method: The extraction of leeches was optimized by orthogonal experiment and countercurrent circuit extractive technique

with titer detected by anti-thrombin activity as an index

and using of membrane separation technology to refine extract. Result: The best technology was to extract five hours with 12 times the amount of 0.9% sodium chloride solution

and extract three times. Selected membrane with 30×１０３ and 0.5×１０３ could achieve the purpose of the purification. Conclusion: The extraction and purification technology was stable

reasonable and practicable.