Abstract: In this paper,a method of logic database design-E-S-C transformation method is presented, which is based on entity-relationship model. Each step of the method can be implemented by algorithm,which is convenient for developing logic database system. An extended entity-relationship model is discribed,and a simple entity-relationship model and a Canonical entity-relationship model are defined. The transformation rules from extended entity-relationship model to simple entity-relationship model is given, then the transformation rules from simple entity-relationship model to canonical entity-relationship model. An automatic tool of logic database design using E-S-C method has been developed.