With the rapid development of computing and communication technology and the rising ratio of the aged, the research on elderly care by using smart home has widely aroused attention. Smart home is designated to provide adaptive and personalized service for the users in home environment. This paper aims to realize the personalized services in smart home environment for the elderly based on situation analysis technology. A new class of context, situation is defined, and its representation and modeling are presented. We then describe the context match method for situation recognition based on different relevant contexts. A personalized service is built on the basis of the result of situation analysis.