More and more enterprises and organizations have been using social media service platforms (such as WeChat public platform) to promote user engagement behaviors (like, comment, etc.)for publicity and marketing. However, there is no clear understanding of the influencing factors of users' engagement behaviors and their different effects. Taking WeChat public platform as there search object and drawing upon Elaboration Likelihood Model, the paper investigates the influencing mechanisms of the central route (information quality) and the peripheral routes (source credibility and emotional factors) on user engagement behavior intention (sharing and adoption). In order to test the proposed hypotheses and research model, alarge-scale scenario-based survey was conducted among users of enterprise WeChat public platform. The results show that: 1) information quality and source credibility both exert a stronger impact on like than oncomment; 2) negative emotion has no impact on comment but has a significantly negative impact on like; 3) the impacts of positive emotion and source credibility on user engagement behaviors are stronger than those of information quality.