Diabetic nephropathy is one of diabetic microvascular complications with increasing incidence in recent years.With the deepening of research，the collateral disease theory has been increasingly applied in clinical treatment.This theory was put forward by Ye Tianshi，a famous physician in the Qing Dynasty.The most important point of collateral disease theory is chronic disease involving collaterals.Diabetic nephropathy is developed from long-term hyperglycemia，which is the premise of involving collaterals.Long-term illness causes deficiency and stasis.The collaterals are stratified and extend to the kidney as kidney collaterals，which are thin and present crossing and wandering distribution.Pathogenic factors are easy to get in but hard to get out of kidney collaterals，which lead to the formation of blood stasis.Modern medical studies have proved that the formation of blood stasis is associated with microcirculation disturbance，dysregulation of coagulation factors，inflammatory response，oxidative stress，platelet dysfunction，and hemorheological changes.In the system of traditional Chinese medicine，diabetic nephropathy is classified as a collateral disease with the pathogenesis of collateral deficiency and blood stasis.Blood stasis is a key factor in the occurrence and development of this disease.According to the theory that collaterals are in function only when dredged，the therapy of tonifying deficiency and dredging collaterals can be combined with pungent herbs，vine herbs，insect medicines，and blood-activating medicines to tonify kidney collaterals in the treatment of diabetic nephropathy.Such therapy can alleviate the symptoms and improve the quality of life of the patients.