Shaft structure design is to determine all reasonable shape and structure size of shaft, and important step in the design for shaft. It by axis parts type, size and locations, parts installed on the fixed way, the nature of the load, direction, size and distribution of bearing types and sizes of axis of blank, manufacturing and assembly process, installation and transportation, the shaft deformation and other factors. Designer to design according to the specific requirements of shaft, when it is necessary to do a few scheme comparison, in order to select the best design scheme, the following is a general shaft structure design principles: 1, save material, reduce weight, using strength, such as size or shape as far as possible big cross section shape coefficient of the cross section; 2, precise positioning, stable, easy to shaft parts assembly, disassembly and adjustment; 3, adopt various measures to reduce stress concentration and improve the strength of the structure. 4, easy processing and manufacturing, and ensure accuracy.