The invention discloses a water supply system of medical purified water with high quality. The water supply system comprises a quartz sand filter, a full-automatic softener, a raw water tank, a booster pump, a plate heat exchanger, an active carbon filter, a precision filter, a primary high-pressure pump, primary RO (reverse osmosis) devices, a secondary high-pressure pump, a secondary RO device, a buffer water tank, a buffer water pump, an EDI (electrodeionization) device, a purified water tank and a circulating water supply device, which are communicated with a water inlet in sequence, wherein the quantity of RO membranes of the primary RO devices is more than that of the RO membranes of the secondary RO device. The water supply system has the beneficial effects that the primary RO devices and the secondary RO device are ensured to work normally through matching of the quantities of the RO membranes; a middle water tank between the primary RO devices and the secondary RO device is reduced, thus reducing the risk of water pollution; the EDI device is adopted, thus ensuring the effluent quality of purified water; and pure steam sterilization is adopted as the sterilization method of a purified water circulating pipeline, so that the sterilization effects are good.