NOVELTY - An ammonia synthesis catalyst comprises ruthenium and polyol, ruthenium complex; water soluble multi-aldehyde; ammonium nitrate of alkali metal of sodium, potassium, rubidium, and/or cesium; and rare earth nitrate, acetate, hydroxide, or graphitizing activated carbon as carrier.    USE - An ammonia synthesis catalyst.    ADVANTAGE - The preparation is simple, high production efficiency, energy-saving and environment-friendly, and easy to realize mass production.    DETAILED DESCRIPTION - An ammonia synthesis catalyst comprises RuL + M1+ M2/AC, M1-(RuL + M1+ M2)/AC, (RuL + M1+ M2)- M1 + /AC, or (RuL + M1 + M2) -M2-M1/AC.    RuL=ruthenium and polyol, ruthenium complex;    M1=water soluble multi-aldehyde, acid generated by the reaction including barium nitrate, acetate, magnesium nitrate;    M2=ammonium nitrate of alkali metal of sodium, potassium, rubidium, and/or cesium; and    AC=rare earth nitrate, acetate , hydroxide, or graphitizing activated carbon as carrier.    An INDEPENDENT CLAIM is included for a method for preparation of ammonia synthesis catalyst comprising mixing ruthenium powder, salt, and a nickel crucible at 400-650 degrees C for 1-4 hours to obtain ruthenium potassium (the potassium salt is potassium nitrate and/or potassium hydroxide at a mol ratio of 1:1-10:1), and preparing the side edge in the alcohol/aldehyde/acid water solution into the ruthenium potassium water solution ruthenium alcohol/aldehyde/acid complex, polyol, polybasic acid, glycol, propanetriol, trimethylolethane, pentaerythritol, xylitol, sorbitol, glutaraldehyde, oxalic acid, tartaric acid, or citric acid; using nitric acid, acetic acid, oxalic acid, citric acid, tartaric acid, or ammonia water to adjust the ruthenium-polyol per pH value of aldehyde/acid complex solution to 1-8; adding alkaline-earth metal or rare earth metal nitrate or acetate mixed solution (the mass percent of acid adjusting solution is 10-65%, and ammonia is 10-25%); graphitizing activated carbon dipped in the mixed solution at 0-60 degrees C for 3-60 minutes; and drying for 20-60 minutes at 50-120 degrees C.