Abstract: A hydrotherapy apparatus, which utilizes the configuration between a sprinkler piping, a reflow piping, a sterilizing piping and a drainage pipe and the operation of a medical motor to control the concentration of a fluid mixture of a medicament and cold water such that each cleaning and sterilizing process does not need to replenish water, saving much time and avoiding waste of water resources. Further, the hydrotherapy apparatus enables the medicament fluid to be maintained at a predetermined concentration to provide a sufficient sterilization effect, and can effectively and completely drain off waste water after the cleaning process, preventing cross-infection between different users.