For small modular reactors, containment suppression devices can be used to limit the rapid increasement of temperature and pressure in the containment caused by loss of coolant accidents (LOCAs). However, temperature stratification may occur in the suppression pool with the change of the mass flow flux and water temperature during the process of discharge, which reduces the heat and mass transfer. In this paper, an experimental facility for temperature stratification of suppression pool is established. The effects of steam mass flow flux, submerged depth of sparger and gas-water volume ratio on the temperature stratification characteristics in the pool are studied. Results show that there is temperature stratification in the pool at a wide range of steam mass flow flux. With the increase of mass flow flux, the influence on stratification is weakened, and the thermal interface moves down, leading to more water participating in heat exchange. With the increase of the submerged depth of sparger, the position of thermal interface moves down and the stirring effect of water is enhanced. As the gas-water volume ratio increases, the thermal interface moves down and the disturbed area enlarges.