Now many industry use of the drawing software,such as the construction,machinery,electricity.In order to improve work efficiency,we need convert two kinds of graphics,for instance the interconversion between geographic information figure and AutoCAD graph,but many kinds of drawing software did not provide conversion interface for each other.This paper established a kind of model of heterogeneous graphics data format conversion based on expert system,through the graphics conversion comprehensive database records the real-time state in the whole switching cycle,analysises and constructs the graphics conversion knowledge base,guarantee the comprehensiveness and correctness of knowledge base become a key,design graphics conversion reasoning mechanism based on forward reasoning strategy.The innovation point of this paper is that expert system are introduced in heterogeneous graphics conversion.Solved the convertion between different kinds of graphics data format,and take DoubleFox figure and AutoCAD graph in oil field for example,complete the transformation of different kinds of graphics.