The dissolver is an important equipment to ensure the dissolution of fuel pellets into solution in head-end of spent fuel reprocessing. The flow of air in the dissolver chute is complicated, and when the flow is abnormal, the air flow carrying the fuel solution flows upward, which affects the stable operation of the spent fuel reprocessing. In this study, the computational fluid dynamics method is used to simulate the airflow in the dissolver chute in the head-end process, and the airflow velocity and nitrogen oxide distribution in the chute are analyzed under the condition of different intake flow rates and different nitrogen oxide exhaust peak value. The results show that the distribution of air velocity at the dissolver chute is not uniform, and the change is drastic at the position of the tee pipe. Most of the nitrogen oxides can be discharged from the negative pressure outlet, and a small part of the nitrogen oxides flow into the top of the chute, and when the nitrogen oxide production increases, the possibility of airflow up-channeling increases. Increasing the intake flow rate can effectively reduce the occurrence of nitrogen oxide gas channeling.