Abstract: Abstract：The soil eco-geochemical baseline is a reference standard for evaluating the geochemical micro-effect induced by artificial disturbance. It has great significance in regional eco-geochemical survey and evaluation and environmental geochemical research. The paper presents the soil eco-geochemical baseline with the soils of alluvial plains in eastern China and by using practical methods of experimental study and provides the information of the soil granularity and material composition related to the baseline. Further study indicates that the features of the soil material composition macroscopically control the regional distribution characteristics of the soil eco-geochemical baseline.