Objective:To solve the difficulty of head and tail orientation in crayfish mechanized treatment.Methods:A crayfish head and tail orientation method was proposed by using the difference of crayfish head and tail shape, which was composed of a roller conveying and grading mechanism. The morphological parameters and orientation mechanism of crayfish were analyzed, then a simple head and tail orientation test device was designed and manufactured; Taking the orientation success rate (head down capture rate and tail down pass rate) as the evaluation index, the effects of capture net angle, orientation slot width and mesh size on the head and tail orientation of crayfish were explored.Results:With the increasing of mesh angle and mesh size, the capture rate increased and the passing rate decreased; With the increasing of the width of the directional groove, the capture rate decreased and the passing rate increased; The optimal parameters of the angle of capture net was 55°, the width of directional groove was 4 cm and the mesh size was 12 mm.Conclusion:The design of head and tail orientation device for crayfish is feasible.