Abstract: The coating has been widely used to protect machine parts from corrosion. The coating of agricultural machinery parts can also improve the reliability and prolong the lifespan of the machines. Drying is therefore the key link for coating parts. However, the temperature and temperature uniformity in the drying room are important factors affecting the drying of coatings. There are two major problems with the designed drying room: the average temperature of the drying room is lower than the target temperature, and the temperature in the front and rear of the drying room is lower than that in the middle. As a solution, velocity and temperature fields are optimized with theoretical analysis and computational fluid dynamics at an early stage. At a later stage, six temperature sensors are installed in different locations on the 0.6 and 0.8 m monitoring surfaces. After the temperature reached the set value and was maintained for 30 minutes, the data collector recorded the temperature data of each temperature measuring point every 1 minute. 30 groups of temperature values were collected within 30 minutes. Through the data acquisition of the velocity field and temperature field, the test results were compared with the simulation results. Comparative analysis of simulation and test results showed that the air supply temperature promoted the temperature rise. Linear adjustment of air supply temperature in the temperature range of 50-150 °C significantly increased the average temperature and reduced the difference between the average temperature and the target temperature. In addition, the air supply speed had a promotion effect on the temperature rise. The temperature rise effect was better when the air supply speed increased from 14 m/s to 17 m/s. However, the temperature did not increase significantly when the air supply speed increased from 17 m/s to 20 m/s. There are 12 combinations of air supply temperature and speed parameters, among them, the wind speed is 14 m/s when the temperature is 62.3 °C, 14 m/s when the temperature is 93.2 °C, 20 m/s when the temperature is 124.1 °C, and 17 m/s when the temperature is 155 °C meet the temperature and temperature uniformity requirements of the drying room. The maximum difference between the simulation and test values was 2.83 °C, and the temperature error was less than 2.5%. Therefore, the simulation results are accurate and reliable, providing a reference for optimizing air supply parameters. Furthermore, a deflector was added to both ends of the air supply port in the front and rear of the drying room because the temperature in the front and rear was lower than that in the middle. The front and rear parts of the air supply outlets provide three different angles of the deflector so that we can study the partition of the temperature control. The simulation results show that when the angle was set to 30°, the deflector improved temperature uniformity to the front and rear of the drying room. The test results can verify the reliability of the CFD method. CFD method provides a theoretical basis for the structural design and parameter selection of agricultural machinery parts drying room to reduce the research cost and realize the scientific and efficient technical application.