Abstract: In to explore the longitudinal migration mechanism of polycyclic aromatic hydrocarbons (PAHs) in soils with different organic matter gradients, we used widely distributed fluvo-aquic soil, cinnamon soil and brown soil in Shandong Province as the research objects, prepared cleaner soils with low (17 g/kg), medium (30 g/kg) and high (45 g/kg) organic matter levels, and contaminated soils with original diesel fuel, and used indoor soil column leaching experiments to simulate the longitudinal migration of PAHs in soils under natural conditions, and analyzed the content and composition of PAHs in cleaner soils and contaminated soils after leaching. The results showed that PAHs were easier to migrate downward in fluvo-aquic soil, and there was no significant difference between cinnamon soil and brown soil (P>0.05). PAHs were mainly concentrated in the surface layer of clean soil column (69.10%-73.68%), and the content of PAHs decreased with the increase of soil column depth; the migration ability of PAHs in low ring PAHs was higher than that in clean soil under deionized water condition. Compared with low organic matter conditions, the leaching rate of PAHs was reduced by 20.43%-32.41% under medium organic matter conditions and by 48.16%-58.05% under high organic matter conditions. The study showed that low-ring PAHs are easy to migrate downward, while high-ring PAHs are more difficult to migrate downward, and organic matter will inhibit the longitudinal migration of PAHs in soil, and the higher the organic matter content, the stronger the inhibition effect on longitudinal migration of PAHs.