This paper introduces the clinical experience of Professor Nan Zheng in the treatment of diabetic nephropathy( DN). Based on the pathogenesis of “kidney collaterals impaired by toxin and pathogenic factors remaining in Moyuan”, Professor Nan Zheng treats the disease by the basic methods of eliminating pathogenic factors from Moyuan, nourishing kidney and removing toxical material, and expelling pathogenic factors to dredge collaterals as well as the methods of relieving sore-throat to remove toxic materials, treating diseases of the lower part by treating the upper part of the body, enteroclysis and warmly purging water toxin. So the purpose of harmonizing yin and yang, regulating qi and protecting primordial qi of the kidney is achieved.