Now, the prophase preparation work of PCA process planning takes longer time, and it is prone to errors and lacks of through consideration and optimization. In addition, PCA process planning does not retain abundant knowledge and experience by good technological tool and means. This situation has no longer been suitable for the current development speed of PCA product. The purpose of this paper is to satisfy with efficient PCA process planning by using expert system technology with PCA process characteristic. A PCA process design-making expert system based on knowledge is designed and developed. This paper also shows system work-flow, knowledge management and process decision-making flow in detail.