The invention relates to a method for controlling nitrogen oxide emission of a gas turbine. The method comprises the following steps that 1) when the NOx emission is greater than 48 mg/m<3>, humidification devices of three air inlets are all operated; 2) when the NOx emission is greater than 42 mg/m<3> and less than 45 mg/m<3>, the humidification devices of two air inlets are operated, and another air inlet is switched in turn so as to ensure that one air inlet is in the drying and regeneration process; and 3) when the relative environment humidity is less than 40% and the NOx emission is less than 50 mg/m<3>, the humidification devices of two air inlets are operated, and another air inlet is switched in turn so as to ensure that one air inlet is in the drying and regeneration process. The method for controlling the nitrogen oxide emission of the gas turbine has the beneficial effects that an atomization and humidification device is additionally arranged outside an air inlet small chamber of a gas compressor of the gas turbine, and a logic condition is set, so that when the device operation condition is triggered, the atomization and humidification device is started, a booster pump is used for atomizing the water meeting the requirements through an atomizing nozzle and then spraying the water, then the air inlet humidity is increased, and the emission of nitrogen oxides of the smoke gas of the gas turbine is reduced.