In this paper we provides an overview of KBASE ?a knowledge base system supported by a relational database management system. It follows a safe and efficient query-evaluation approach of compiling the query-patterns given by the user into Relational Algebraic Processing (RAP) trees. After the whole architecture and the inferrence mechanisms of KBASE is presented, we describes thoroughly the rule normalization technique used in KBASE. Three kinds of normal form are clarified. The transformation algorithms and good properties of each kind of normal form are also given.