Abstract: A new approach to case retrieval for case-based process planning based on matching geometry of parts is proposed. A model of Form Vector Adjacent Matrix(FVAM) is built upon boundary representation(B-rep) to represent geometry of parts. On the basis of FVAM, a formal definition of case model is put forward and an effective indexing scheme is presented in terms of key parameters used to describe FVAM features. Methods are explored to measure both form similarity and case similarity. Finally, algorithms of case retrieval are presented. This approach has the advantage of generality and applicability, and the feasibility of the method has been proved in practical applications.