Abstract: A new method of knowledge acquisition based on 2 and a new type of knowledge representation-knowledge matrix are advanced in this paper, which are based on personal construct psychology(PCP). We give out a new triangle product formula of composite fuzzy implication relation from the reality example and a RGD1I algorithm of relation graph description in order to elicit and refine relevant knowledge of domain expert. The algorithm and formula have been successfully applied to KMKAS knowledge acquisition system. As a result, we have implemented an advanced language select system and machine tool property select system. The KMKAS system provides a new way of knowledge acquisition.