A 3 200 t/d new type of dry-process cement production line in Jilin was chosen as the research object. The simulation was carried out by using Ansys-Fluent software. Based on the thermal law inside the precalciner, the factors influencing ammonia denitrification were explored. The effects of ammonia injection height, ammonia injection rate, ammonia injection angle, ammonia nitrogen ratio, ammonia water atomization particle size, ammonia injection depth and nozzle number on the out-of-stock effect were studied. The experimental results show that the optimized ammonia injection height is 42 m, the ammonia injection rate is 80 m/s, the ammonia injection angle is 0°, the ammonia nitrogen ratio is 1.8 and the ammonia water atomizing particle size is 100 μm, the ammonia injection depth is 750 mm, the number of nozzle is 4, evenly distributed along the circumference of 90°. Under this optimized working conditions, it can achieve the denitrification efficiency of 76.89%.