Abstract: The optical scanning mirror is a key component in laser scanning detection system.The purpose of the paper is to introduce the theoretical analysis,parameter selection and design method of the rotatory polyhedron scanning system.The fundamental requirements to construct a rotatory polyhedron scanning system are much high geometry or manufacture accuracy,very small rotatiry deformation of the rotation components.Finally,this paper discussed the scanning effectiveness,and point out that the selection of scanning effectiveness is in the range of 0.4～0.6,and how to select other relative parameters.