This invention discloses a two-step process for producing melamine from urea under normal pressure. The method comprises: (1) blowing urea with ammonia into a reactor, mixing with ammonia from a circulation machine, preheating and blowing the catalyst from the bottom of the reactor to fluidize; (2) discharging the reactant from the top of the reactor, removing the catalyst dust by an outer filter,introducing into a collector, cooling naturally and condensing to obtain melamine; (3) purifying the circulation gas from the collector with an absorbing column to absorb carbon dioxide; (4) reactingthe mother liquor obtained in step 3 and carbon dioxide obtained by the decarbonization of ammonium bicarbonate to obtain ammonium carbonate; (5) cooling the purified circulation gas, introducing into the circulation machine, concentrating, and passing into the reactor. Compared with present techniques, the method has such advantages as low raw material cost, high profit, easy control, simple process and reliable operation.