Cloud and Internet of Things incorporation (IoT), referred to as Cloud IoT, has been deemed an enabler for Lots of distinct implementations. Nevertheless the suspicion of the security problem is one of the key issues that some organizations are hesitant to implement such technologies, while some simply dismiss the technologies. security problem when incorporating Cloud IoT into their business. Therefore, given the numerous choices of cloud-resource providers and IoT devices, how to evaluate their security level becomes an important issue to promote the adoption of Cloud IoT as well as reduce the business security risks. In order to solve this issue, we are designing an end-to-end security assessment system based on Software Defined Network (SDN) to determine the security level for the provided Cloud IoT offering, considering the value of business data in Cloud IoT. Specially, in order to simplify the network controls and focus on the analysis about the data flow through Cloud IoT, we develop a three-layer framework by integrating SDN and Cloud IoT, which consists of 23 different indicators to describe its security features. Then, industry and academic interviews are conducted to recognize the value of these features for overall protection. In addition, our system can efficiently determine the level of protection that can assist customers in their Cloud IoT collection, provided the related evidence from the Cloud IoT offering, Google Brillo and Microsoft Azure IoT Suite.