The utility model provides a circulating material conveying system which comprises a material box conveying mechanism which comprises a material box feeding system, a material box discharging system and a movable material box workbench, the material box feeding system is used for conveying material boxes for the material box workbench, and the material boxes are used for conveying pipe shells; thematerial block circulating conveying mechanism is used for conveying material blocks in a circulating mode, the material blocks serve as carriers of the tube shells, and feeding, lead bonding and discharging of the tube shells are achieved through the material blocks in the circulating conveying process of the material block circulating conveying mechanism; shell picking and recycling mechanism,and the tube shell picking and recycling mechanism is connected with the material box workbench and the material block circulating conveying mechanism and can pick up and place tube shells so as to achieve back-and-forth position change of the tube shells between the material boxes and the material blocks, and after all the tube shells in the material boxes on the material box workbench are bondedand put back, the material box workbench moves and conveys the material boxes into the material box discharging system. The circulating material conveying system has the advantages of being high in production efficiency, beneficial to rapid switching of round pipe shells of various sizes and the like.