【Objective】Thermal desorption technology is widely applied in the remediation of petroleum-contaminated soil. However, the significant differences in the thermal desorption characteristics due to different types of clay mineral, significantly impact the setting of process parameters and the efficiency of thermal desorption. Thus, this study aims to clarify the differences in thermal desorption mechanisms among various petroleum-contaminated clay minerals and to guide the determination of application parameters for thermal desorption engineering.【Method】In this study, contaminated soil with typical clay minerals including montmorillonite, chlorite and kaolinite were prepared to investigate the thermal desorption kinetic properties, and characterize their microstructures to explore the differences in thermal desorption and the influencing factors. 【Result】The results showed that the thermal desorption of three contaminated soil could be divided into three stages. Phase I (30 ℃-110 ℃), in this phase, montmorillonite and chlorite exhibited a three-dimensional diffusion desorption mechanism, while kaolinite followed a first-order kinetic desorption mechanism. The activation energies (Ea) were 58.64, 124.96 , and 75.22 kJ mol-1, respectively. Phases II (110 ℃-370 ℃) and III (370 ℃-520 ℃) followed a first-order kinetic mechanism. 【Conclusion】The physicochemical properties and microstructure of clay minerals are the main parameters accounting for the differences in their thermal desorption characteristics. Montmorillonite mainly relied on azeotropic stripping, diversion diffusion, catalytic cracking, and interlayer structure adsorption, which promoted the thermal desorption of petroleum hydrocarbons. The influencing mechanism of chlorite involved physical barrier and catalytic cracking, showing an inhibitory effect at temperatures <200 ℃. However, thermal desorption of petroleum hydrocarbons was promoted when the temperature was >200 ℃. The influencing mechanism of kaolinite was mainly chemical adsorption, which generally inhibited the thermal desorption of petroleum hydrocarbons. This study provides theoretical guidance for determining the thermal desorption process parameters of petroleum-contaminated soils containing different types of clay minerals.