Abstract: Through the geochemical study of Se in rocks, soils and plants in northern Liaoning Province, the paper analyzes the release-migration-absorption of Se in rock-soil-plant. The results indicate that the average Se content in rocks is 0.08×10^-6. For different rock types, the Se contents generally show the rule of volcanic rock > carbonate rock > granite/sedimentary rock > metamorphic rock. Vertically, the Se content shows the variation of soil layer A > soil layer B > pedogenic mother rock. The average Se content in topsoil is 0.24×10^-6, with the general pattern of brown soil (A&B layers) > paddy soil (A&B layers) > meadow soil (A&B layers) > aeolian sandy soil (A&B layers); The average Se content in plants is 0.07×10^-6, with the soil Se enrichment capacity of plants in the order of weeds > hazelnut > paddy rice > corn. There are significant positive correlations between soil and rice, soil and hazelnut, but no obvious correlations between soil and weeds, soil and corn.