Abstract: Internet of Things, IoT, is a new technical hierarchy system combined by several information technologies. IoT is known as the third wave of global information industry after computer and Internet. The applications of IoT in agriculture are required by the modern agriculture development. This paper introduces the IoT's concept, the system framework, the development, and the applications in agriculture. Furthermore, this paper analyses the key technologies of agriculture IoT, including the sensor networking technology, the identification technology, communication technology and the intelligent processing technology, and points out the existing challenges and development directions of the above technologies.