Control system is the core of the smart home technology. The networking and informatization of smart home system all require it. This paper studies on a control system in smart home system based on ARM which includes two environments, LAN and WAN. Private IP is used in LAN environments, and dynamic domain name server (DDNS) which is provided by Peanut hull is used in WAN environments for control functions. In both environments, smart home can be controlled through computers and Android smart phones.