Abstract:  In order to solve the problem of high energy consumption in direct thermal desorption treatment of organic contaminated soil with high moisture content, this study proposes utilizing the waste heat of the treatment process for soil pre-drying to reduce moisture content. This research focuses on soil contaminated with polycyclic aromatic hydrocarbons (PAHs) and employs non-isothermal drying characteristic tests, pollutant precipitation tests, and rotary drum dryer drying characteristic experiments to investigate the soil drying process and pollutant precipitation characteristics. The results reveal that: (1) The non-isothermal drying process includes two stages: acceleration and deceleration drying. The critical temperatures were obtained under heating rates of 5, 10, 15, and 20 ℃/min. At a heating rate of 5 ℃/min, the critical temperature and soil moisture content were the lowest, at 66.7 ℃ and 2.57%, respectively. This suggests that the optimal soil drying is achieved at low heating rates. However, this increases the drying time, (2) Consequently affecting the soil treatment capacity. The rotation speed of the dryer significantly influences soil retention time. As rotation speed increases, retention time decreases, resulting in larger soil treatment capacities. At rotation speeds of 1, 2 and 3 r/min, the outlet temperatures of the soil are 107.7, 103.9, and 101.9 ℃, respectively, all surpassing the critical temperature. Due to the strong disturbance caused by the lifting plates within the dryer drum, the outlet moisture content of the soil remains relatively low across all three rotation speeds, aligning well with non-isothermal drying test results. (3) When initial soil moisture content is 12.10%, 16.05% and 24.03%, the outlet soil moisture content is 0.23%, 0.27% and 0.22%, respectively, indicating that the dryer can achieve satisfactory drying results over a wide range of initial moisture content. (4) Due to the high boiling points of PAH pollutants, they are not easily precipitated during the soil drying process. (5) According to the heat transfer calculation, when the initial soil moisture content ranges from 12.10% to 24.03%, the volumetric heat transfer coefficient of the dryer is between 89 and 98 W/(m³·℃). This study demonstrates that utilizing a rotary drum dryer to dry PAH-contaminated soil can significantly reduce soil moisture content, decrease thermal desorption energy consumption, and the drying process is not easy to precipitate pollutants. These findings can provide theoretical and design guidance for the application of rotary drum dryers in contaminated soil drying.