In order to solve the problems of the existing wireless detection system cannot accurately and effectively reflect the environmental changes of the three-dimensional space in the greenhouse, as well as the large positioning error of the sensor node and the high hardware cost, an intelligent greenhouse three-dimensional temperature and humidity detection system was designed based on ultra wide band (UWB) positioning. The system located each sensor node through a self-designed STM32F system board integrating UWB positioning module, and it was equipped with AHT25 high-precision sensor to collect environmental data. The UWB main base station used the 4G network communication module to send the sensor data and location information to the host computer, and visualized the three-dimensional temperature and humidity field of the greenhouse according to HTML5 technology on the Web side to complete the remote detection of the three-dimensional temperature and humidity of the greenhouse. The system positioning test proved that the accuracy of each sensor node was mainly concentrated in the range of 10~30cm, the measurement position error of some nodes is greater than 50cm, the maximum packet loss rate of each node was 2.5%, and the average packet loss rate was 1.9%, which met the basic needs of greenhouse measurement and is of great significance for detecting greenhouse thermal defect areas and studying the suitable environment for plant growth.