Based on the problems in the current greenhouse environmental monitoring system such as difficult connection layout, low flexibility and high costs, this paper builds the greenhouse environmental monitoring system based on wireless sensor network, and designs the sensor nodes and gateway nodes. The sensor nodes of this system are responsible for collecting environmental parameters and sending the data to gateway nodes via wireless sensor network. And the gateway nodes transmit the data to the remote monitoring platform. The microprocessor module of node hardware uses MSP430F149 microprocessor for data processing and control; wireless communication module consists of nRF905 RF chip and peripheral circuit, responsible for transmitting and receiving data; sensor module uses AM2301 sensor for data measurement; the power supply module uses the circuit consisting of LT1129-3.3, LT1129-5 and Max660 to provide 3.3 and ±5V power. The C language development is employed for wireless routing protocol of node and time synchronization algorithm, to achieve node data acquisition and processing, rule forwarding and remote transmission. Remote monitoring software uses NET.ASP, HTML and C# development to provide visual WEB mode remote data management platform for users. The system goes through networking testing in greenhouse in Xining City, and test results show that the system operation is stable and reliable, and the average network packet loss rate is 2.4%, effectively solving the problems in greenhouse environmental monitoring system and meeting the application requirements of greenhouse cultivation environmental monitoring.