Plants usually required specific environmental conditions for their growth. It is therefore necessary to put those conditions under control. This paper presents control systems of temperature, humidity and light in greenhouses at low cost. The system can meet production need in Vietnam. In addition, the paper also illustrates a greenhouse model design which is compatible with Vietnamese economic and geographical conditons. On the other hand, designing a greenhouse frame, and a structural support system enables automatically controlled parameters such as temperature, humidity and light intensity. These parameters are automatically collected by a central controlling unit using microcontroller, PID controller and sensors arranged in the greenhouse design to monitor and correct control signal. The design has been also successfully experimented in Dalat city of Vietnam.