The progression of internet has bring much convenience in our daily lives and changed the educational environment. Long gone are the days when people get knowledge from newspaper, magazines, books, or traditional classroom resources. Today, people get on internet to find what they want to know. Recently, more and more teachers are using virtual classroom platforms on internet to facilitate the interaction between teachers and students. An interesting phenomenon was observed that there are relatively large differences in utilization of various virtual classes, even though use the same platform. This thesis applies data mining techniques to investigate the factors affecting students' use of virtual classrooms. The experimental results show that teachers are the most important factor in affecting students' use of classrooms.