Abstract: The constitution method of technological module in intelligent CAPP(computer aided process planning) and the implement of databank and reasoning machine are proposed and discussed. The module adopts OPS (official production system) as the expert system tool and combines the knowledge expression language based on rules with the procedure language so that the rules of procedure knowledge is easily expressed, hence the rules of producing type are used to establish knowledge database and the deductive reasoning machine is adopted, rasulting in the realization of a series of technological decision making.