Pelleting is an effective way to store and utilize organic fertilizer. A key step is to dry after pelleting. At present, onezone rotary drying is often used for drying organic fertilizer pellets. But it has many problems, such as high energy consumption and etc. To guarantee the efficiency and high quality of the organic fertilizer in drying process, a triplepass rotary drum drying technology was introduced. Therefore, the problems of long overall length, large occupied area and low plant utilization factor can be solved. This study combines the advantages of triplepass rotary drum dryer. To explore the relationship among the residence time in the drum, the structure parameter of flight, and the drum installation angle, the EDEM software was used to simulate the movements of the pellets in the drum. The principle of the flight was analyzed, and a new type of combined flight was designed. The residence time in middle drum testing apparatus was set up, and the singlefactor experiment design was conducted. Then, the significant factors on residence time were obtained by using orthogonal experiments, which turned out to be the drum installation angles and flight angles. The results of the simulation and experiment were compared, and it’s verified a very highly prediction on the residence time and optimized parameters of the drum installation angle. Finally, the experiments showed that the installation angle should be less than 5° and flight angle should be higher than 40°.