Energy-saving raw water heating system

The invention relates to an energy-saving raw water heating system which comprises a closed water subsystem, an open type water subsystem and a raw water heating subsystem. The closed water subsystem is respectively connected with the open type water subsystem and the raw water heating subsystem; moreover, a branch is led out of a closed water return mother tube of an outlet of a closed water pump, and a certain volume of closed water is led out to a raw water heater to heat raw water; after the closed water is cooled, the closed water is returned to the suitable position on a closed water supply mother tube at an outlet of a closed water heat exchanger. According to the invention, waste heat in the returned closed water in a closed water system is utilized to heat the raw water, so that steam consumption is reduced; meanwhile, the closed water is cooled so as to meet the requirement on the temperature on production. Moreover, consumption of open type water for cooling the closed water can also be reduced so as to reduce power consumption of an open type water pump; the energy-saving raw water heating system has the advantages of energy saving, environmental protection, simple system, no limitation to the type of a unit, flexibility for control and regulation and the like.