The invention provides a method and system for safe cloud computing. The method comprises the steps that user property configuration is conducted on the client side; a right control tree is generated and the user role right is controlled; a user logs in a PaaS platform server to submit the user property of the client side and the right control tree to the PaaS platform server; the server verifies the identity of the user when the user requires to have access to the PaaS platform server, and controls the access of the user to the PaaS platform server according to a verification result. According to the method and system for safe cloud computing, a method for property encryption deployment in a PaaS platform is provided, malicious stealing of a database on the PaaS server side is prevented, and the safety of enterprise user data is effectively improved.