Enterprise Cloud Computing (ECC) is a new trend for IT service provisioning due to the concerns of cost down and increase of Quality of Service (QoS). However, there are many obstacles to the services moving from traditional enterprise computing to cloud environment, such as how to assure the quality of services, security, data availability, data privacy, etc. In order to support the risk free migration of IT provisioning for enterprises from traditional enterprise architecture to cloud computing, an integrated solution is urgently needed. In this paper, we propose a formal model, to assist not only the ECC services design and construction through SaaS, PaaS, IaaS, but also the simultaneous monitoring and dynamic analysis on the QoS factors for the promises from QoS service providers, such as security, performance, timeliness, throughput, reliability, and the service level agreements (SLAs) for multiple ECC consumers. Based on the formal model, analysis model and testing model can be generated consequently to support automatic testing as well as run time monitoring to assure the satisfaction to the requirements/SLAs constraints.