The invention relates to an external traditional Chinese medicine for preventing and treating phlebitis caused by chemotherapeutic medicines. The external traditional Chinese medicine consists of the following raw material medicines in part by weight: 40 to 80 parts of sanguisorba carbon, 30 to 60 parts of weeping forsythia, 30 to 60 parts of rhubarb, 40 to 80 parts of cutch, and 40 to 60 parts of borneol. The external traditional Chinese medicine is prepared by the following steps of: crushing the raw material medicines respectively, and sieving the medicines through a 200-mesh screen respectively to obtain powder of each raw material medicine; selecting the powder according to the weight proportion of each raw material in the external traditional Chinese medicine formula, mixing the powder, and uniformly blending to obtain traditional Chinese medicine powder; and blending the traditional Chinese medicine powder with sesame oil to prepare uniform paste, applying the paste at an intravenous injection position externally, binding with a bandage, performing chemotherapy, and releasing the bandage after the chemotherapy is completed. The external traditional Chinese medicine has the advantages of simple preparation, low cost, wide medicine sources, convenient use, quick response, high cure rate and no toxic or side effect, is suitable for preventing and treating the phlebitis caused by the chemotherapeutic medicines, and has the clinical application effective rate of 98.15 percent.