data mining;  Expert systems;  cost estimates;  Classification;  Forecast

The classification and prediction technology is applied to the mechanical product design database data mining, the product cost prediction model based on the decision tree is established for the key factors affecting the cost of various components, and the rule base of the expert system is adjusted through data mining in combination with the expert system, so that the rules of the expert system can not only come from the summary of expert experience, but also from the mining of previous product data, which broadens the way of knowledge acquisition and improves the efficiency of knowledge acquisition. Finally, a framework of product cost evaluation system based on classification and forecasting technology is given.