In the process of pepper drying, the airflow intensity and uniformity in the mesh-belt pepper dryer will affect the quality of pepper after drying. The results of pepper parameters were measured by experiments to set the parameters of porous media. The flow field model of the drying chamber was constructed by ANSYS Fluent and the reliability of the model was verified. The average velocity and non-uniformity coefficient M were used to characterize the airflow intensity and uniformity of the drying chamber. The porous media model was used to simulate the flow field of the meshbelt pepper dryer before and after structural optimization. The results showed that the adjacent air inlets of the original structure of the mesh-belt dryer were arranged in opposite directions, which caused the airflow to disperse and converge to produce eddy current. The pressure at the airflow confluence was increased, the airflow flow was blocked, and the flow velocity was decreased. The flow velocity at the center of the eddy current was extremely low, resulting in the unevenness of the overall flow field. According to the airflow distribution characteristics of the mesh-belt dryer, a structural optimization scheme for increasing the deflector was proposed. The change of the deflector angle increased the average velocity of the airflow and reduced the nonuniformity coefficient. When the deflector angle was 0 °~7.5°, the drying chamber had the best airflow intensity and uniformity, so the deflector deflection angles were set to be 0°, 2.5°, 5°, and 7.5°. The influence of four angles of the deflector on the airflow in the drying chamber was analyzed. When the angle of the deflector was 2.5°, the airflow distribution was optimal. Compared with the original structure, the average velocity increments on the XY, XZ, and YZ planes of the dryer were 6.8%, 10.8% and 5.2%, respectively, and the non-uniformity coefficient was reduced by 8.7%, 8.5% and 2.7% on average.