Some small modular reactors' containments are placed in the pools for long term cooling. The flow and temperature distribution in the cooling pool are of great importance for heat removal from the containment. In this paper, studies were performed experimentally and numerically. In the experiment, a scaled test facility was used to simulate the containment and its cooling pool, where thermocouples were used to measure the temperature at various locations and Particle Image Velocimetry (PIV) was used for the measurement of the flow velocity. CFD simulations were performed, where standard k-epsilon, realizable k-epsilon, DES and SST models were used for sensitivity analysis and realizable k-e model was used for transient simulation. The experimental results showed in the cooling pool the temperature had large difference in the vertical direction while had little difference in horizontal direction during long term cooling condition. The velocity increased rapidly before 300 s because of natural convection. As time went on, thermal stratification occurred and the velocity started to decrease because thermal stratification impeded the natural convection circulation. The experimental results were compared with the numerically calculated results, and reached a good agreement. (C) 2018 Elsevier Ltd. All rights reserved.