Abstract: Considering response time,one of the important indicators for measuring QoS of cloud computing services in SLA,in this paper,we propose a dominant strategy incentive compatibility mechanism.Assuming all the cloud resource providers being rational,the proposed mechanism in this paper ensures each cloud resource provider is willing to bid true resource cost information,and taking this as the prerequisite the cloud service provider can derive a way aiming to the shortest response time under the cloud user’s budget constraint and also choose optimal composition of resource providers for user’s job.Finally,we prove pivotal properties of mechanism proposed in the paper and present the optimization algorithm of response time.