According to the winter operation problem of circulating water system in a power plant, this paper expounded the composition and the function of circulating water system in 300 MW heating unit, analyzed the influence of circulating water’s inlet temperature on host vacuum, proposed the energy-saving optimization measures in winter which was applying quick closing-adjusting device of spring energy storage and bidirectional adjustment of wind shield, as well as solved the problem of large power consumption of circulating water system. After the implementation of the energy-saving measures, it can save large integrated auxiliary power, which plays a key role in the economic operation of the unit.