Phase change material (PCM) is receiving significant attention for the ability of storing thermal energy in recent years. In order to better understand the heat and mass transfer of PCM during solid-liquid phase change process and then improve the application of PCM, in this paper, the solution of solid-liquid phase change problem of PCM is investigated by using lattice Boltzmann method (LBM). A thermal LB model for describing the solid-liquid phase change phenomenon has been established and verified by the solution of conduction phase change under constant heat flux. Three kinds of heat flux distribution on left wall have been investigated: uniform distribution, linear distribution and parabolic symmetry distribution. The simulation results showed that concentrating more energy on upper region of left wall can reinforce the clockwise convective circulation. More input energy concentrating on the middle of left wall is the effective way to accelerate the rate of solid-liquid phase change and maintain the temperature of PCM. (C) 2015 Elsevier Ltd. All rights reserved.