The utility model relates to a device for preparing nitrogen oxide through ammonia oxidation, which mainly solves the problems of low nitrogen oxide generation quantity and low product concentration in the prior art. In order to solve the problems, the utility model adopts the technical scheme that the device comprises a gas distribution region, an ammonia oxidation furnace, a quench cooler and a separator which are sequentially connected in series, wherein the gas distribution region comprises an ammonia gas distribution region 1-1, a water vapor, oxygen gas and nitrogen gas distribution region 1-2 and a mixer, the ammonia gas distribution region 1-1 and the water vapor, oxygen gas and nitrogen gas distribution region 1-2 are respectively connected with a mixer inlet, and a mixer outlet is connected with the ammonia oxidation furnace, wherein the ammonia gas distribution region 1-1 comprises a liquid ammonia tank, an ammonia evaporator, a desulfurizer, an ammonia heater and an ammonia filter which are sequentially connected in series, the water vapor, oxygen gas and nitrogen gas distribution region 1-2 comprises a heater 11 and a filter which are sequentially connected in series, the heater 11 is provided with a water vapor, oxygen gas and nitrogen gas inlet. The device can be used for industrial production of preparing high-concentration nitrogen oxide through ammonia oxidation reaction.