Water circulation system for low-load stable operation of once-through boiler

The invention discloses a water circulation system for low-load stable operation of a once-through boiler. The water circulation system comprises a steam-water separator, a water storage tank, a recirculation pump, a high-pressure heater, a water feeding pump, a coal economizer, a water cooling wall, a superheater, a steam-water heat exchanger, a steam turbine and a reheater. The steam-water separator is connected with the water storage tank and the superheater, the water storage tank is connected with the recirculation pump, the water feeding pump is connected with the high-pressure heater, the economizer is connected with the water cooling wall, and the water cooling wall is connected with the steam-water separator. The steam-water heat exchanger is respectively connected with the recirculation pump, the high-pressure heater, the economizer and the steam-water separator; the steam turbine is connected with the superheater; the reheater is connected with the steam turbine and the steam-water heat exchanger.