This study aims to realize the issues of increasing number of high school students access Facebook. We used simple random sampling technique to collect 1,206 valid samples in New Taipei city, Taiwan. The fuzzy statistics was used to determine the student users’ behaviors and the level of their safety awareness on Facebook. The result reveals both boy and girl students agreed that entertainment and information needs of Facebook using are relatively safe. However, the virtual feeling related using on Facebook is less reliable than do the others. The result shows that the students’ Facebook using and its security awareness has positive fuzzy correlation. Most students are aware of possible consequences of providing personally identifiable information to the Facebook, but nevertheless feel comfortable using it. This study suggests that the teachers and parents do need to take care of those students why they spent two or over three hours on Facebook. Do the student users realize their privacy and security properly on Facebook? It needs to be treated and viewed carefully. This study also provides an example of interval data transformation with fuzzy correlation to interpret this issue.