Bone erosion is a major factor leading to joint deformity and loss of function in rheumatoid arthritis（RA） patients. Doctors later often treat bone erosion form the kidney as affected by the theory‘kidney governs the bones and engenders marrow’in Huangdi Neijing（Inner Canon of Huangdi）. Modern TCM syndrome research shows that damp-heat stasis obstruction is the main pathogenesis of active RA. Magnetic resonance imaging（MRI） and other modern imaging examinations have showed that bone erosion occurs in the early stage of RA. The core pathogenesis of bone erosion in active RA is damp-heat stasis obstruction.