Abstract: At present, the communication protocol of the agriculture Internet of Things (IoT) is not uniform. To pack and transmit agricultural information better, a suitable protocol of the IoT, i.e. AGCP (Agricultural Greenhouses Communication Protocol), was proposed for agricultural communication, and an agricultural greenhouse monitoring system was designed using AGCP protocol combined with IoT. AGCP includes a set of data communication format, and defines the parameters in the protocol. There are variable design used for the data transmission which is collected by sensor, and command parameters used for equipment control, as well as function parameter which represents status and the function of sensor. Taken advantage of AGCP, firstly, a wireless sensor network for data transmission based on ZigBee technology was designed, which was used as coordinator in the perception layer. Secondly, terminal node core packaging, acquisition function node, such as temperature and humidity sensor, and the control function node, such as pump, were designed respectively. Then the agricultural environment information acquisition and equipment control by terminal had been realized. Thirdly, in functional module, communication protocols of the specific function modules were designed based on AGCP and characteristics of different modules, so the light control module, temperature control module, irrigation control module were detailed designed respectively. Finally, Android system was designed as mobile terminal with various core classes. The architecture of the UI interface, initialization, network communications, sensor equipment and automatic control were realized, respectively, which were used for remote monitoring on mobile terminal. The system test and analysis had been carried out in an agriculture park of Qingyuan city, Guangdong province. All kinds of sensor data from agricultural greenhouses were recorded at 12 pm, April 7, 2016. The greenhouse temperature, the humidity, the concentration of carbon dioxide, the light intensity, the soil temperature and humidity were 21.4 ℃, 65.3%, 867 mg/m3, 690 Klux, 20.06 ℃ and 6.6%, respectively. Furthermore, from the historical record of different sensor data, it was shown that carbon dioxide concentrations in agricultural greenhouse changed quickly, but kept steady in a short period. The temperature was risen gradually. On the contrary, humidity was declined, while light intensity, temperature and humidity also maintained stable, which were in accordance with local environmental characteristics at that time. Additionally, the generator of carbon dioxide, water pump, fan, and fill light were successfully controlled by setting. It is shown that the system can collect the agricultural environment information, including the air temperature, humidity, carbon dioxide, soil moisture and the corresponding equipment automatic control, with very good performance. The results verify the effectiveness of the AGCP protocol in the Internet of things of agriculture as well as the feasibility of building the system.