It is a common situation that the liquefied gas tanks are always heated by the outer hot environments, which affecting the safety of the tanks. In this paper, numerical studies were conducted to reveal the heat transfer characteristics of this circumstance. The coupled heat transfer process among the thermal environment, the tank wall and the fluid in the tank was thoroughly investigated by simultaneously solving the temperature fields of both the solid region and the fluid region as well as the flow fields of both the liquid phase and the vapor phase inner the tank. The results showed that affected by the near wall flow and the wall boiling, the heat transfer presented different patterns in the stable thermal stratification stage and the de-stratification stage. In the stable stratification stage, the heat flux from the liquid phase wall to the medium distributed uniformly along the axial direction of the tank, while in the de-stratification stage, it differed a lot at the different positions. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.