Aiming at the problems in the development and implementation of Networked Sale and Customization system by small-and-medium enterprises, the study on ASP development supporting Platform of Networked sale and Customization system for small-and-medium enterprises has been done. The whole frame of ASP development supporting Platform of Networked Sale and Customization system for small-and-medium enterprises was proposed. Then a series of function modules of this platform was designed. At last, ASP-based service model and development service workflow for small-and-medium enterprises was created. And, this platform has been applied in dozens of enterprises.