Smart home system is now widely used in our houses, offices and etc. but those existing products are mostly wired，which causes inconvenient installation and high cost.Therefore we propose a wireless smart home
system based on Internet of things，which aims at expanding the range of network users from people to things，eventually making the automatic process of information transmission among things come true. In other words,
things could communicate automatically. Our smart home system has a thre-layer structure, which includes front end sensor layer, network layer and user service layer.The sensor layer consists of entrance guard，cnvmonmcnt
monitors and household-appliance controllers, all these devices support ZigBec communication protocol. Houschold- appliance controllers arc integrated into according remote controllers, in order not to modify appliance itself.The
network layer consists of EEE802. 15.4 (ZigBee)，a control terminal and global system for mobile communications (GSM)/general packet radio service(GPRS).Control terminal is in charge of information gathering and
distribution. A secure digital memory card is used to record every single event. The front end sensors connect to the control terminal over ZigBec network in a star topology.The terminal plays the role of coordinator, which is a full-
function device. And all the front end sensors arc normal reduced-function devices. Wireless ranscciver is performed by JN5139，which is a low power, low cost wireless microcontroller suitable for ZigBec.The user service layer
provides human-device interactions.Tcrminal controller supports bidirectional communication with users over GSM/ GPRS by integrating Sicmens MC35i module，which is a supper slim dual-band GSM communication module; it
supports standard attention command set. Records could be checked by using keyboard and liquid crystal display of terminal.The whole smart home system functions in this way; once front end sensors detect anything unusual，they
would notify the control terminal immediately over ZigBec network. After receiving a notification, the control terminal would parse it，and send a text or multimedia message to user’s cell phone over GSM/GPRS network if
necessary, In the opposite direction, if user wants to control a household appliance, the only thing he needs to do is to send a formatted text message to control terminal. After receiving and parsing the message，the control terminal
understands user’s intention correctly.Then terminal would send commands to corresponding household-appliance controller over ZigBec network. All communications in our smart home system are wireless，so there’re no wires
needed during installation. Human-device interactions arc mostly done over the GSM network, which has the widest coverage in this country. This makes sure our system is able to provide higlrquality service even in some remote regions.