The average scheduling strategy based on task numbers in fault-tolerant has shortcoming such as processing span and Quality of Service(QoS). Aiming at this problem,this paper proposes a grid scheduling algorithm based on priority,and then puts forward the design scheme of the hierarchical cluster system. The algorithm introduces the task in the process of task scheduling,task execution time remaining concept value density,cost budget and span,to make up for the task scheduling in the treatment of two span a...