The disclosure of user identification password can endanger information data in a role-based access control (RBAC) policy. In order to achieve access control action for the users, a RBAC policy on dynamically adjustable trust degree is proposed. The policy combines a trusted computing theory with access control policy. Firstly, an analytical hierarchy process is adopted to evaluate the trust degree of the system. Then, a dynamical regulation method of a trust degree is introduced to make the user’s trust degree a foundation of the system while assigning user's roles. This model is applied to a virtual database experiment. The result shows that through the implementation of the trusted access control, it is possible to effectively improve the security of database.