With the prosperity of the Internet and WWW, lots of web sites have been raised. The eBusinessWeekly 2000 reported that “web portal” was with highly proportion (46.1%) among all kind of the websites; this reveals that web portal would be the place where Internet users visit most often. Since the Internet is widely popular, user’s perception to use such WWW technology was easy to understand. In this research, we study the personality trait of self-monitoring on the Internet web portal usage behavior. Thus, we focused on the concept of self-monitoring in exploring the attitude, web self-efficacy, intention and web portal usage to see the variation in this concept. The combined dataset shows that attitude toward web portal and web self-efficacy are significant impacted on intention, and actual web portal usage is significant influenced by both intention and web self-efficacy. Further, the differences between high self-monitoring (HSM) group and low self-monitoring (LSM) group are observed and have significant di inct in our research model, therefore two moderating hypotheses are both supported. Base on the research findings, conclusions and implications are discussed.