Virtual communities (VCs) grow rapidly and have become one important platform of knowledge sharing recently. Members browse the community forum and find out that certain opinions posted by others have difference with members’ views. Members will consider whether to participate in the discussion to reduce the uncertainty and resolve doubts in their mind or browsing the discussion by others. This study proposes that: in order to solve the inconsistency, members may actively participate in the discussion or passively follow up the discussion initiated by others. Through expressing their opinions and discussing with others, members can learn from communication, clarify the truth, get a consensus with others members, and reduce the uncertainty. On the other hand, through merely following up the discussion posted by others, members can generate the feeling of enjoyment. Both behaviors contribute members’ subjective well-being. This study further analyzes the above issue in terms of two types of members: active participants (posters) and passive participants (lurkers). Data collected from 391 valid users of PTT Bulletin Board System provide strong support for most of these hypotheses. Empirical results show that users tend to browse post which consistent with their views, and also tend to reply post which consistent with their opinions. Moreover , expressing their opinions and discussing with others, members can learn from communication, clarify the truth, get a consensus with others members, and reduce the uncertainty. On the other hand, through merely following up the discussion posted by others, members can generate the feeling of enjoyment. Both behaviors contribute members’ subjective well-being. However, posters’ subjective well-being significantly more than lurkers, proof of concept of "more blessed to give than to suffer," this study encourage users to participate in VCs activities, and knowledge sharing to increase well-being. Than suggested that the managers of VCs should be encouraged lurkers convert to posters by changing knowledge sharing atmosphere of VCs, enhancing the depth and breadth of VCs.