Abstract: To study the freezing process and thermal changes on reservoir ice cover, icing tests were conducted with different air temperature and water depth conditions in the reservoir placed in a constant-temperature laboratory. The freezing time, the vertical distribution of temperature and the thickness of ice cover were measured during the tests to study the effect of different air and water depth conditions on freezing processes, thermal changes on reservoir ice cover, water temperature, and temperature distribution in the ice cover. The results show that temperature is a major influential factor on the ice cover regime. The ice thickness is linearly proportional to the accumulated hours under negative temperatures. The water depth has an impact on the onset of the freezing process, but its effect on thermal changes on reservoir ice cover is marginal. During ice growth, a linear temperature gradient can be observed in reservoir ice cover. The slope of ice temperature increases with the decrease of air temperature. The distribution of water temperature under reservoir ice cover remains unchanged during the melting period.