In this study, we propose an expert system aided model necessary for extracting the rules, which can diagnose the success level of new product development project. For this purpose, first, we design a classification model to analyze the characteristics of $\ulcorner$parts development projects$\lrcorner$. Second, in order to select success factors, we explore literatures and interview with project managers working at large sized companies of electronic parts. And we conduct the enquete survey and statistical analysis to extract key success factors. Third, in order to decide the level of project success, we use the concept of 'Recearchitivity' as a framework of judgement criteria. Fourth, in order to extract diagnosis rules, we use expert system development tool.