On the basis of a synoptic analysis of the Ontopia knowledge suite and the architecture of the Ontopia topic map engine,this paper does an in-depth analysis of the interrelations between the development package and the core interface of engine API and the ways of implementation. In view of the support of the Ontopia engine interface for Topic Maps in its establishment,storage,data exchange,development of application,etc,the author makes a comprehensive analysis of the mechanism of the engine API in combination with specific code.