Abstract: In order to reuse the CAD data efficiently，the paper presents an effective method for extracting mechanical part information from existing mechanical engineering drawings produced by CAD software.Characteristics of the forms in the engineering drawings are analyzed.A new method to represent arbitrary forms with matrix is proposed，which makes it easy to extract form frames.Based on the form frames，the part information is obtained.In addition，a practical software tool is briefly introduced，which can be used to extract part information from AutoCAD produced engineering drawings automatically.