A novel technique of fault diagnosis on greenhouse environment control system (GECS) was developed for more reliability. Major faults of actuators, sensors, switch board and control software in GECS were analyzed and listed. All GECS faults were divided into four grades according to their damage levels, and were treated respectively with different strategies and solutions. Two working modes, ‘fast fault diagnosis’ and ‘complete fault diagnosis’, were proposed to meet the requirement of both higher accuracy and rapidness. The idea of one-key setting was applied for different users. The intelligent programming was completed to carry out the fault diagnosis on GECS. The test results show that the faults are correctly detected and identified.