Cloud computing is attractive and popular. Constructing high-quality cloud appliance is a serious explores problems. QoS (Quality-of-Service) grading supply precious data for constructing most favorable cloud check assortment from a set of functionally correspondent check applicant. To acquire QoS standards, real-world invocations on the check aspirant are frequently essential. To evade the time-consuming and exclusive real-world tune invocations, this manuscript suggest a QoS grading calculation structure for cloud services by enchanting benefit of the precedent service procedure incident of extra clients.