Although the number of users has been growing exponentially in SNSs, some SNSs are facing a financial crisis and might be shut down in the near future. Therefore, understand users' incentives to switch to another SNS has great influence on operators' business performance. The study extended "Push-Pull-Mooring" migratory theory to explain the switching behaviors of users in SNS. Structural equation modeling will applied to analyze data collected from a filed survey. The result can construct a solid switching framework and help operators to understand their customer better.