The invention discloses a chilled water storage device comprising a chill storage water inlet/chill discharge water outlet, a guiding slide bar, a separating plate, a chill storage container, and chill storage water outlet/chill discharge water inlet. The chill storage container is an closed structure, the guiding slide bar is fixed in the chill storage container, the separating plate sleeves on the guiding slide bar and can slide along the guiding slide bar to separate the chill storage container into two totally isolated portions which are a chilled water storage portion and a warm water storage portion, the wall, at the cool water side, of the container is provided with the chill storage water inlet/chill discharge water outlet, and the wall, at the warm water side, of the container is provided with the chill storage water outlet/chill discharge water inlet. When chill is stored/discharged, the separating plate slides along the slide bar under the function of pressure difference of a circulating water pump, thermal stratification occurs in a common chilled water storage device can be eliminated, chilled water storage devices can be used in parallel in conditions with different capacities because of the closed structure, and the chilled water storage device also can be made into different shapes and sizes to be freely assembled on site, so the chilled water storage device is high in space utilization rate, good in place adaptability and capacity adaptability and high in storage and chilling efficiency.