The paper mainly analyzed the development of site leveling optimization design with the combination of Visual Basic. NET and AutoCAD, also it gave a detailed introduction on how to build up the optimal design in the establishment of mathematics model. The emergence of the AutoCAD ActiveX technology has made Visual Basic. NET possible for the second development of AutoCAD. On the original working basis, the develpoment of "the site leveling optimization design and automatic painting system" on the web basis, simple and convenient, user friendly, will relieve the professionals of the tedious calculation and plotting work, and will raise the efficiency of project designing.