It is crucial to integrate Internet of Things (IoT) with cloud computing to build Smart Cities. However, there are few cloud platforms dedicated for IoT environment in Smart Cities. And existing cloud platforms are complex and difficult to implement with a small scale. Therefore, in this study, we propose a scalable cloud model for Internet of Things (IoT) based on the concept of modularization and service integration. Different from general clouds, the cloud model can be implemented on a small scale in the initial phase, and be extended and integrated in the future. For the resulted cloud platform, we assume that Intelligent City Areas (ICAs), which serve as the basic components of Smart Cities, are the application domains. We also depict the hardware deployment architecture and software implementation model for the cloud platform using Service- Oriented Architecture (SOA) and modular design method. Finally, we demonstrate the effectiveness of our proposed method by designing and deploying a kid safety support system for kindergartens.