Abstract: Establishing dynamic trust relation is the beginning of interaction and cooperation among entities under large scale distributed environment.The computing of t Trustworthiness in current trust dynamic level scheduling algorithm is a little rough,and they only research the scheduling algorithms which apply in executing sequence tasks.A new trust dynamic level scheduling algorithm based ontology trust model is presented.It improves the trust computation for different aspects and supports executing composite tasks.Simulation experiments prove that the algorithm can assure the execution of composite tasks in a highly successful level in task scheduling.