The impact of electronic word-of-mouth (eWOM) on consumer purchase decisions in social networking sites (SNSs) has been an very important topic to researchers and practitioners. Friends on the SNSs, via Web connections, conversation, and collaboration, create product recommendations and eWOM. Previously, when consumers needed information, they usually through marketing channels such as TV advertising or network advertising to get product-related information; however, there are more consumers through their friends on the SNSs to get these useful eWOM now. This paper focuses on social relationships (social ties, trust, and identification), social exchange (reciprocity and enjoyment helping), and motivation and ability to access information (motivation to access information and ability to access information) in the SNSs to explore its impact on cognition and affective attitudes, and then have the eWOM effect. The research method is survey, and the research subject is the users on SNSs. We take online questionnaire to investigate these users’ eWOM intention and their opinions. The survey results from 212 participants on the SNS suggest that trust and motivation to access information are positively associated with users’ cognition and affective attitudes, whereas ability to access information only affects the cognition attitudes. In addition, users’ cognitive attitude positively influences users’ affective attitude and eWOM intention. Taken together, the paper provides insight into theses factors that shape eWOM and outlines additional questions that deserve further study.