Though coarse root biomass is an important part in biomass of forest ecosystems, few studies were found in subtropical area. In this study, whole digging method was used to determine the biomass of coarse root (diameter>2 mm) of 175 trees of 8 species in subtropical evergreen forests. The 8 species includes Castanopsis fargesii , Castanopis sclerophylla , Schima superba , Pinus massoniana , Cunninghamia lanceolata , Liquidambar formosana , Sassafras tzumu , Alniphyllum fortunei . Also, the lost roots during excavation were corrected by developing scaling relationship between biomass of root and diameter. Then, four kinds of allometric models for each species and combined trees were fitted to link stem diameter at breast height (dbh) and height ( H ) to coarse root biomass. The results showed that all the scaling relationship between biomass of root and diameter of roots were significant ( P P R 2 values than the height-coarse root biomass. The results also indicate that dbh is an adequate estimator for coarse root biomass of subtropical evergreen trees. The results in this study provide important information to estimate the coarse root biomass in subtropical evergreen forests.