The invention discloses a boiler cold water loop system, and belongs to boiler auxiliary appliances, and the boiler cold water loop system is mainly used for solving the problem that stored water in a boiler water outlet pipeline can not be used. The boiler cold water loop system structurally comprises a water outlet pipe, a water return pipe, a water pump and a water tap, wherein the water tap is arranged at the connected part of the water outlet pipe and the water return pipe; the water return pipe is provided with a water pump for pumping water in a unidirectional mode; and the tail end of the water return pipe is connected into a boiler. According to the invention, the structure that the water return pipe is arranged at the part close to the water tap is adopted, cold water in the water outlet pipe can backflow into the boiler and can be heated again before hot water is received, and waste is prevented.