In the process of reusable component-basedsoftware developing, how to retrieve the most satisfying component among the library of components plays a key role in component library system. It is essential to use component reuse history and offer users. reuse experience to offer users a certain help component. Data mining technologies provide a feasible approach for effective decision support. The application of decision-tree-based classification method is discussed. Through the application of DM technology to the data, the auxiliary decision support is offered to understand and choose the component and the technological guarantee for successful reuse is offered as well.