The invention discloses a CAPP (computer aided progress planning) system of sheetmetal, which comprises a system master control module, a system management module, a user management module, a planning module, a process knowledge management module, a database management module, a system help module, a user work area module and the like. The system adopts a modularized concept in design and has higher development flexibility; a system of the system has good expandability and a maintenance function; the system has a powerful man-machine interaction function and a user interface, and simplicity and convenience in operation, meanwhile the system provides help and learning functions so as to guide a user to complete a sheetmetal process planning conveniently and quickly; the system provides a special auxiliary function module, has high openness and directs to requirements of the user; the system can replace handwork of technologists, complete the preparation and the audit of a sheetmetal machining technology, and reduce the labor intensity of the technologists, at the same time, the system also can ensure the consistency of the technology, improve the preparation efficiency of the technology, and shorten a product development cycle.