With more and more applications of Internet of Things in many domains, it also steps into Smart Homes. In this paper, we propose an Internet of Things-based smart home system for home comfort, leisure and safety. This system uses embedded system, 3G, and ZIGBEE technologies to overcome the drawbacks of current smart home systems such as discrete functions, poor portability, weak updating capability, and personal computer dependence. Moreover, the system architecture is presented, and the design of its gateway is shown in detail from hardware to software.