Abstract: Professor Xu Zhi-yin's clinical experience in diagnosing and treating breast cancer-related lymphedema concluded that postoperative breast cancer lymphedema is deficiency in root and excess in manifestation. Considering it is deficiency in the root, its pathogenesis is closely related to the liver, lung and spleen, and the main pathogenic factors are blood stasis, qi stagnation, and water-dampness. Based on the treatment principle of reinforcing healthy qi and expelling the pathogenic factors, the specific treatments are established, such as benefiting qi, nourishing blood, unblocking the collaterals, as well as promoting urination. Clinically, the Honghuang decoction is the basic formula. In addition, physicians need to distinguish the manifestations and root causes, to keep a sense of proportion, to focus on the individual treatment, to modify the decoction according to the syndrome changes, and to choose medicinals on the grounds of different constitutions. In conclusion, physicians should follow the idea of "treating disease before its arising", which is strengthen the healthy qi and eliminate potential harmful factors to prevent the occurrence or development of a disease, to achieve the best therapeutic effect.