Abstract: By defining software’s requirements from different standpoints, requirement definers often get partial requirement specifications （viewpoints）. Because of the independence of viewpoints, viewpoints’ integration is an important and difficult problem in requirements engineering. Viewpoint integration can be auto-processed when viewpoints’ requirement and relations of viewpoints are formularized. In this paper, an SFSM state transition diagram is to describe viewpoint’s requirement. Viewpoints’ relations are described in the guard condition of the state transition diagram. A method of checking and handling inconsistency among viewpoints based on SFSM is also presented. According to the conflict of the equivalence relation of states and the integrated state transition diagrams, requirement definers can check and handle viewpoints’ inconsistency. The set of viewpoints can be integrated to the requirement specification of the whole software system after requirement definers repeat the process of integrating viewpoints and handling inconsistency. In this paper, an example of telephone system is presented to illuminate the process of viewpoints’ integration. Using this method, requirement definers can automatically achieve viewpoints’ integration and can be educed to check and handle viewpoints’ inconsistency.