NOVELTY - A dissolved oxygen in boiler water supply is removed by extracting hydrogen from synthesis ammonia vent gas in synthesis ammonia production process by utilizing hydrogen extraction device; introducing tail gas after being subjected to hydrogen extraction into lower part of stripping tower so that from bottom to top; conveying oxygen dissolved in water and tail gas together to three-waste furnace, carrying out water sampling and analyzing, discharging deoxidized water into deoxidizing water tank and sending deoxidized water to a boiler by boiler high-pressure pump.    USE - Method for removing dissolved oxygen in boiler water supply.    ADVANTAGE - The method has greatly reduces water energy consumption and reduces production cost. Exhaust gas resources in synthesis ammonia production are adequately utilized to carry out deoxidization on the boiler water supply. The water energy consumption in deoxidization is substantially decreased.    DETAILED DESCRIPTION - Dissolved oxygen in boiler water supply is removed by:    (A) extracting hydrogen from synthesis ammonia vent gas in synthesis ammonia production process by utilizing hydrogen extraction device;    (B) introducing tail gas after being subjected to hydrogen extraction into lower part of stripping tower so that from bottom to top, where tail gas is countercurrent contact with water containing oxygen which flows from top to bottom;    (C) conveying oxygen dissolved in water and tail gas together to three-waste furnace or a blowing air recovery device to recover latent heat from dissolved oxygen and tail gas; and    (D) introducing deoxidized water after being subjected to gas stripping into water tank at lower part of stripping tower, carrying out water sampling and analyzing, discharging deoxidized water into deoxidizing water tank after dissolved oxygen is less than or equal to 15 mg/L, and sending deoxidized water to a boiler by boiler high-pressure pump.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic diagram illustrating a method for removing dissolved oxygen in boiler water supply. (Drawing includes non-English language text).