Software development process consists of five phases : requirement, analysis, design, implementation and testing. There is almost always a gap between the system design and implementation stages, caused by a combination of the difficulty of programming and frequent changes on the system design. The goal of this paper is to reduce the gap between system design and implementation, and we design a tool producing a application program by recognizing business logic for a more rapid and flexible developing of software. The core idea of Application Program Generator is : firstly, to recognize that business application in the same domain share business logic and presentation logic : secondly, to treat system design as persistent meta-data ; thirdly, to use the persistent meta-data to build or customize applications as required.