Abstract:TRIZ theory is a way to solve the problem of innovation，it is used to solve the conflict problem of technology in the design by innovation.The article which adopts contradictions in the technical theory of TRIZ designs a new shrimp roll grading machine with the dispersive and directional device.This machine solves the problem of the original shrimp grading machine，which covers a large area and is used to a restricted field.The improved shrimp grading machine cuts down area of about 1/3 than the original.Through contrast test，classification accuracy is slightly increased and damage rate is slightly reduced than the original machine.The structure is simple and improved easily on the original machine，it has a certain promoting significance.