In order to help cloud users find services more suitable for their own and reduce the cost of these services, this paper tries to establish a cloud service agent model based on Service Level Agreement (SLA). It first proposes a framework of cloud service agent, and studies the game model for SLA negotiation and the queuing model for SLA monitoring. Simulation results show that, both the game model for SLA negotiation and the queuing model for SLA monitoring are effective for the cloud service agent model based on SLA.