Abstract: The software AutoCAD2004 was introduced. On the Visual Studio 2003 platform, using the visual C++ language, an ObjectARX program had been written, and a 3dimensional parametric modeling had been accomplished. Taking the trolley frame of crane as example, a fast design system for trolley frame of crane with variable structure had been developed; and the working efficiency of the designers can be improved by using this system.

Key words: ObjectARX program, Software AutoCAD, trolley frame, parametric modeling, structure analysis