The study is based on Information Systems Continuance Model and combines with perceived enjoyment, privacy mechanism, and trust to investigate continuance intention of using Instagram among high school students. The results indicate that users' confirmation has significantly positive effects on perceived usefulness and perceived enjoyment. Besides, users' confirmation, perceived usefulness, perceived enjoyment and trust have significantly positive effects on satisfaction. Especially, trust has most positive effect on satisfaction. Moreover, users' perceived usefulness, perceived enjoyment and satisfaction have significantly positive effects on continuance intention. Satisfaction has most positive effect on continuance intention. In addition, privacy mechanism has significantly positive effects on trust. In contrast, trust has no direct effect on continuance intention, but it can indirectly influence through users' satisfaction.