Numerical Control (NC) machining is an important process for modern automation. Lots of Computer-aided Manufacturing (CAM) systems are widely used in NC machining. Most of these kinds of software are able to generate the NC codes automatically and import these codes to the control unit of a NC machine center. Parameter setting for generating the NC codes is the key procedure for post process of the CAM system. The paper employs Java language to develop an expert system delivered via the web. Java-swing components in Java Foundation Class (JFC) are used for designing the query interface and displaying the query results. Some critical query information such as working material, cutting tool material and tool diameter is imported to the system. Two critical expertise parameters, tool spindle speed and feed rate, for post process of a computer-aided manufacturing system which generates the NC codes will be provided.