In present, plenty of solar greenhouse in northern China can't play maximum efficicency because of have no environmental control system. Through greenhouse construction for many years, a new practical HMG-2 type solar greenhouse with environmental automatic control system has been developped. This control system has "offline" and "online" two kind of working modes. The paper expounds the key technology adopted by the control system, which can greatly improve production performance of solar greenhouse. This environmental control system has many advantages such as low cost and easily to implement. It can meet the demand of users and has popularization value.