The invention discloses a method for identifying prawn head points and prawn tail points in a prawn picture quickly and precisely. Firstly, preprocessing for colorized prawn pictures which are collected on line is conducted to obtain initial outlines, then polygon approximation is conducted to reduce the number of outline points, and a point set S1 is formed; then convex hull detection is conducted, outline points which are located on prawn abdomens are removed, and a point set S2 is formed; then included angle outline analysis is conducted, and a point set S3 is formed; finally, the intersection of the point set S2 and the point set S3 is obtained, and the outline points in the intersection are obtained and used as prawn head points and prawn tail points of the prawns. The method has the advantages that prawn head points and prawn tail points of the prawns can be extracted quickly and effectively, and the correct recognition ratio is high.