In the research of viewpoint-oriented requirements engineering, viewpoints are closely related to domain and requirements information. To identifying viewpoints reasonably and effectively, this paper integrates viewpoint-oriented research with domain-oriented research and presents a method for identifying viewpoints based on domain and viewpoint deputy. In this method, viewpoints are extracted from domain model after the domain model has been build, and viewpoint deputies are established according to the classification of requirements information, thus different kinds of viewpoints can be identified with different viewpoint deputies. In addition, this paper also briefly introduces how to check and integrate viewpoints based on viewpoint deputies.