Since the internet appears at the start of 1990s, the society has been changed. Nowadays, the internet has already become an essential part in modern life. The real world¡¦s interpersonal communication, sharing behavior and other interaction ways are all appeared in the internet virtual world. The Virtual Community verified this phenomenon. The Virtual Knowledge Community provided internet users convenient ways to seek useful information. Take the largest Virtual Knowledge Community in Taiwan¡ÐYahoo¡IKimo Knowledge¡Ï as example, its reaching rate exceeded Google Taiwan in only about one year, since the website was launched at the end of 2004. Obviously, the knowledge search service played a very important role in Taiwan. It seems that people can use this service originated from the concept of Web 2.0 to improve their own knowledge experience. However, the virtual world is fictitious because it is filled with good and bad information. Can people distinguish them? Will it influence the users¡¦ cognition and the ability to judge? The research is developed under this issue, adopting Content Analysis method to survey the Best Answers in Virtual Knowledge Community. It tried to prove and find out how the ability of people¡¦s information judgment under the Web 2.0 tendency is. The research found that the Best Answers in different categories are different in their argumentation structure. First, in the category of ¡§Evidence¡¨, the structure is obviously different between the ways Best Answers chosen. Best Answers chosen by asker pay much more attention to evidence than those chosen by voters. In addition, the category of ¡§Information Offering¡¨ played an important role in Best Answers. The significance is more conspicuous than Argumentation Backing and Emotionality Backing. Does it mean the answers provided more information will be chosen as Best Answer more easily? It also reminds us that even the internet and information technology bring this society many advantages and benefits, but we must train ourselves to have depth think and judgment ability, too. Or we will fall into Information Smog and lose our judgment ability.