Abstract: The general processing for unload rock sections is rather inconvenient and difficult, especially for sedimentary rocks, because that the rock sections are very liable to break up, difficult to be cleaned off and lower efficiency. Based on dunking and leaching of the thin-section by organic solvent in closed system at the normal pressure and constant temperature, a new method with Soxhlet extraction has been put forward. The new method provides the advantages of more efficiency, more convenience and environment-friendliness.