Firstly, a multilevel trust algorithm for MANET (mobile ad hoc networks) is presented in this paper and the trust level is defined as a three-tuple type in this multilevel trust algorithm. The paper introduces the multilevel trust into MANET, thereby controlling restricted classified information flows among nodes that have different trust levels. Secondly, the infrastructure of MANET that suit to our multi-level trust is presented. Some conclusions are given at lastly. Firstly, a multilevel trust algorithm for MANET (mobile ad hoc networks) is presented in this paper and the trust level is defined as a three-tuple type in this multilevel trust algorithm. The paper introduces the multilevel trust into MANET, information flows among nodes that have different trust levels. Secondly, the infrastructure of MANET that suit to our multi-level trust is presented. Some conclusions are given at lastly.