The indexing cam mechanisms have been widely used in machine tools, because of the advantages of simple structure, automatic positioning , arbitrary static and dynamic ratio, and help to achieve complex movement, but the disadvantages of the indexing process are that the indexing angle is determined by the position number and it can only index one angle and one direction，besides, it neither can achieve stepless indexing nor satisfy the requirements of the workbench travel bidirectional rotation in some cases. A new type of mechanical indexing mechanism was designed taking gear and oneway bearing as the main drive connection mode, which not only satisfied the need of the stepless indexing, but also satisfied the requirements of the workbench travel bidirectional rotation. The 3D model of the mechanism was designed and the motion simulation was achieved by UG software, and the rotation condition of the turntable was observed, which verified the feasibility of the scheme theoretically. The research provides theoretical basis for the research of diversity and engineering prototype.