Objective　To enrich the clinical anatomical research methods related to tendon by using protease digestion technique to make vascular casting of retained tendon.　Methods　0.5%, 1.0%, 1.5% and 2.0% concentrations of protease mixture were used respectively to decompose palmaris longus muscle and the suitable basic concentration was selected. The forearm vascular casting specimens were filled with acrylic resin and perfused to make casting specimen. After the filler was coagulated, the forearm vascular casting specimens were soaked into the protease solution mixture with the 1.0 % initial concentration and then during the soaking period, 35 g of alkaline protease powder was added to the mixture every 24 h, after 5 days corrosion, the forearm vessel casting of  the retained tendon was made. Results　Through the decomposition of the palmar longus muscle tissue，we found that the protease solution mixture with a 1.0 % concentration  could decompose adequately muscle tissue before the tendon fractured. We found that the skin, adipose tissue and muscle tissue basically disappeared. Bones, tendons and cast blood vessels  well preserved, the skin, the source and distribution of blood supply in the superficial layer, tendon and muscle, the relationship between cast blood vessels and skin, superficial layer, tendon and muscle can be clearly observed.　Conclusions　Using 1.0 % protease mixture as the starting concentration and adding protease mixture with 50% of the alkaline protease powder every 24 h is an appropriate corrosion method for making the vascular casting of the retained tendon. The vascular casting of retained tendons is a new type of anatomical skill, can enrich the clinical anatomical research methods related to tendon.