Studies on health literacy and health information behavior of the elderly have become an important issue as China enters aging society and information society. This paper explores the elderly’s behavior of health information adoption. This paper establishes a theoretical model for health information adoption behavior of elderly WeChat users with grounded theory on the basis of in-depth interviews with 40 senior citizens at two colleges for the aged in Zhejiang Province. It fnds that following prominent elements have impact on their adoption behavior: information element, interpersonal element and private element can affect their adoption behavior directly or indirectly through health information credibility. The tactics of adoption behavior is threefold: spatial-temporal strategy concerning current situation, experiential strategy based on traditional culture and health perceptions, and adoption/rejection strategy based on economy and psychology.