Abstract: Authorization is a part of trust management,the existing systems have some faults as follows: one is "one time authorization,effective for ever",the other is authorization depth is not controlled effectively. To address the problems,this paper proposes a multi-level authorization management model in distributed system. This model uses a way based on the trustworthiness to authorize and inspect every entity regularly. To the entities that does not conform the condition,they will be took out. Moreover,the correspondence among the entities is controlled by the authorization root,strengthen the depth control.