Abstract: The expert system of supporting design for tunnel or cavern has important effect on selecting supporting scheme and ensuring the stability of tunnel or cavern. This paper has researched the method to develop the supporting design expert system by integrating CLIPS and VC⁺⁺ .Some key technologies have been introduced including how to store rules by ODBC, how to embed the CLIPS reasoning engine, how to converse the Chinese information and the English information recognized by CLIPS and how to display the supporting drawing on AutoCAD automatically etc. The expert system has been used in supporting design for the 290 tunnel of Nan Fen Open Pit Mine and got good result.