Four subtropical soils/sediments include marine top sediment, river sediment, pond sediment, and paddy soil were collected, and soils/sediments organic matter (SOM) was extracted from the samples with chemical methods.Chemical characterization of SOM shows that soils/sediments organic matter is highly heterogeneous, includes humic acid, diagenetically kerogen, and black carbon.Structure analysis on these SOM reveal that humic acid and kerogen usually formed from organism under reducing conditions.However, Black carbon was produced from the incomplete combustion of fossil fuels and biomass, structurally rigid, physically condensed, and less polar than humic acid and kerogen.Systematic study of SOM heterogeneity will greatly help us to precisely understand the process of biogechemistry and organic pollutant behavior in natural system.