There are dozens of kinds of ammonia synthesis catalyst products, among which the iron-based catalyst is in the absolute position with good activity, good quality, cheap price and long service life.In China, there are more than ten kinds of ironbased catalyst, such as A103, A103H, A106, A109, A110, A201, A203, A207, A207H, A301 and Amomax-10/10H, which areused in ammonia synthesis production successfully.A large number of researches have paid attention to Fe-Co catalysts, rare earth catalysts, ruthenium-based catalysts and Co-Mo bimetallic nitride catalysts. However, in the view of catalyst manufacturing cost and production cost, iron-based catalyst had good success and non-iron based catalyst still only has theoretical significance and it is difficult to replace.No matter which type of iron based ammonia synthesis catalyst, the active ingredients, whether Fe₃O₄, FeO, Fe_1-XO or the pre-reduced catalyst, must be reduced to have catalytic activity.The reduction process is equivalent to the last important step of the catalyst preparation process whose success or failure determines the activity, energy consumption and benefit of the catalyst.Therefore, the reduction process of catalyst is very important, quite“one move accidentally, all lose” meaning.Fe_1-XO-based ammonia synthesis catalyst is one of the most active molten iron catalysts in the world and has been widely used.In this paper, the Fe_1-XO-based Amomax-10/10H composite catalyst was taken as an example to extract the key technology of the heating reduction process of iron based ammonia synthesis catalyst from both theoretical and practical dimensions.In terms of theory, the basic reduction principle of reduction process could be deduced from the characteristics of reduction reaction and the approximate molecular formulas of Fe₉O₁₀ and Fe₉O of Amomax-10/10H were accurately deduced from the angle of iron ratio[w（Fe ²⁺）/w（Fe ³⁺）] and iron/oxygen ratio[n（Fe）/n（O）].From the point of view of high Fe content and low O content, the theoretical basis of Amomax-10/10H with good catalytic activity was analyzed.The excellent low temperature reduction performance of Amomax-10H was explained from the thermodynamic metastable state of the nanoscale passive film and the theoretical basis of high-low matching, easy first and difficult second, hierarchical series reduction was explained.In practice, the reduction operation principles of “two high and four low”, “step heating” and “different temperature and pressure raising at the same time” were followed, which were the necessary measures to stabilize the temperature rising and reduction operation, prevent the water vapor concentration from exceeding the standard and ensure the catalyst activity.