Behind ¡§e-mail¡§, ¡§BBS¡¨, ¡§Instant Messenger¡¨, weblog is regarded as the fourth kind of ¡§killer application¡¨ of the Internet. Therefore, ¡§weblog usage behavior¡¨ becomes a popular issue to study in not only industry but also academia. However, there is still not a complete framework to explain the motivation of blog usage and the influence factors. This research extends the ¡¥Attitudinal Belief Structure¡¦ of ¡¥Theory of Planned Behavior¡¦ and discusses which personal values among social value, utilitarian value, hedonic value and psychological value are the main motivations to use blog. In addition, we look into ¡¥past use¡¦, ¡¥attachment styles¡¦, ¡¥information recipients¡¦ and ¡¥blog type¡¦ deeply to find out which influence factors moderate the research model. This study used survey method to collect data from the Internet users and use PLS to analyze it. The result found the social value and psychological value are significant motivations among four personal values, and the influence of hedonic value is comparatively week. Then, the influence of personal value on blog usage intention is generally weaker among heavier users than among lighter users. Otherwise, psychological value influence people with preoccupied attachment style less. However, when the information recipients of blog trend to intimate friends, psychological value becomes more important. Finally, as types of blog are different, the influence of user¡¦s psychological value on future usage intention will be different. In sum, we extend the ¡¥Attitudinal Belief Structure¡¦ and renew it with social psychological theories to build a complete model. The research model can offer future study a framework to refer, and give weblog .com several marketing suggestions.