The invention relates to an automatic water cooling cup which is used for cooling a hot beverage and keeping the beverage at a temperature suitable for drinking. The automatic water cooling cup comprises a cup bottom, an outer cup wall and an inner cup wall, cup inner space is defined by the outer cup wall and the inner cup wall, and the inner cup wall is supported on the cup bottom; the inner cup wall is formed by a thermal insulating wall body and a thermal conducting wall body, and the inner cup wall is internally provided with a temperature sensing cavity and a sliding cavity; a sliding sealing device is arranged in the sliding cavity to divide the sliding cavity into a first air chamber and a second air chamber, and the sliding sealing device can slide up and down along the inner wall of the sliding cavity; the temperature sensing cavity is of a sealed structure enclosed with air and is communicated with the first chamber through a connecting hole; a fixator is arranged on the sliding sealing device and fixedly connects a radiator with the sliding sealing device, the radiator is a barrel-shaped object made of a thermal conducting material, and the radiator makes contact with the thermal insulating wall body and can slide up and down along the thermal insulating wall body. The automatic water cooling cup can rapidly cool the high-temperature beverage to the temperature suitable for drinking and maintain the temperature for a long time, and the automatic water cooling cup is high in reliability and convenient to carry.