NOVELTY - Iron and ruthenium based catalysts comprises connecting a first iron-based ammonia synthesis catalyst containing column (2), a second iron-based ammonia synthesis catalyst containing column (9), a first ruthenium-based ammonia synthesis catalyst column (16), and a second ruthenium-based ammonia synthesis catalyst column (23).    USE - Iron and ruthenium based catalysts ammonia synthesis method.    ADVANTAGE - The method has low energy consumption and high efficiency.    DETAILED DESCRIPTION - Iron and ruthenium based catalysts comprises:    (A) connecting a first iron-based ammonia synthesis catalyst containing column (2), a second iron-based ammonia synthesis catalyst containing column (9), a first ruthenium-based ammonia synthesis catalyst column (16), and a second ruthenium-based ammonia synthesis catalyst column (23);    (B) heating gas discharge from a circulation gas compressor in a heat exchanger (31) controlled at 380 degrees C, transporting heated gas controlled at 10-15 MPa to the first iron-based ammonia synthesis catalyst containing column controlled at volume space velocity of 1000/hour, discharging gases comprising 3-5 vol.% un-separated ammonia from the first iron-based ammonia synthesis catalyst containing column, conveying discharge gases controlled at a pressure of 14.8 MPa to an ammonia separating system, and reacting 8-13 mass% separated ammonia with hydrogen at a volume ratio of 3-4:1 at 450-510 degrees C in the presence on iron-based catalyst to obtain fresh synthetic gas;    (C) heating fresh synthetic gas at 370-390 degrees C, transporting to the second iron-based ammonia synthesis catalyst containing column at a volume space velocity of 10000/hour, reacting hydrogen with nitrogen at 450-510 degrees C to generate ammonia having a concentration of 13-18 mass%, and discharging gas from the second iron-based ammonia synthesis catalyst containing column;    (D) mixing discharged mixed gas with a fresh nitrogen in a static mixer at a volume ratio of 3-2:1 at 360-370 degrees C, transporting obtained product to the ruthenium-based ammonia synthesis catalyst column at a volume space velocity of 10000/hour, and reacting hydrogen with nitrogen at 400-430 degrees C in the presence of ruthenium catalyst to generate ammonia having a concentration of 19-23 mass%; and    (E) discharging ammonia to an ammonia-cooling device, separating un-separated and unreacted ammonia, hydrogen, nitrogen and argon, and recycling circulating gas to the circulation gas compressor.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic view of an iron-ruthenium catalyst ammonia synthesis method.    First iron-based ammonia synthesis catalyst containing column (2)    Second iron-based ammonia synthesis catalyst containing column (9)    First ruthenium-based ammonia synthesis catalyst column (16)    Second ruthenium-based ammonia synthesis catalyst column (23)    Heat exchanger (31)