In order to improve the cooling effect of the oriented silicon steel constant annealing process, a three-dimensional numerical simulation of the air-liquid two-phase flow inside the air atomization nozzle was conducted. The computational fluid dynamics method was used to analyze the effects of air pressure and liquid flow rate on the velocity and liquid phase volume fraction of the flow field inside the nozzle. The numerical results are in good agreement with the experimental test values, and the maximum error is less than 10%. The results show that when the water flow rate is constant, with the increase of air pressure, the velocity inside the nozzle gradually increases, and the liquid phase volume fraction decreases. The velocity distribution at the nozzle outlet became less uniform, while the liquid phase volume fraction distribution become more uniform. When the air pressure is constant, with the increase of water flow rate, the velocity inside the nozzle gradually decreases, and the liquid phase volume fraction increases. The velocity distribution at the nozzle outlet become more uniform, while the liquid phase volume fraction distribution become less uniform. When the air water pressure ratio is 1.1, the nozzle cooling uniformity is better, and the optimal working conditions for nozzle cooling uniformity are air pressure of 0.2 MPa and water flow rate of 180 L/h.