In order to satisfy the planting requirements of vegetables in north cold area of China, an automatic monitoring and controlling system of greenhouse interior environment was developed. By synthetically considering the temperature, humidity, illumination intensity, CO 2 concentration, and their mutual influences, the system adopts an environmental regulation method based on set point control to automatically control the internal environment of the greenhouse. The system could provide a long-term stable tool to measure and analyze the environmental information in greenhouses. The test showed that the temperature in greenhouse could be maintained at the needed level while the relative humidity and illumination intensity could be controlled within the suitable scope as well.