Summary: A new lattice Boltzmann model is proposed to describe liquid-vapor phase transitions, and then a simulation on condensation and vaporization is performed. The simulation results show that the maximum relative error of the volume fraction of the vapor phase, the liquid phase density, and the vapor phase density is 1.18%, 0.23%, and 0.32%, respectively, for the process of condensation, and 0.08%, 0.48%, and 0.20%, respectively, for the process of vaporization. Compared with previous results, the present results are more close to analytical solutions. In order to further confirm the feasibility to simulate complicated phase transitions with the present model, a simulation on pool boiling and boiling flow in a vertical pipe is conducted. It is observed from the results that small and spherical bubbles grow near the wall and rise due to buoyancy, and collisions and coalescences of the bubbles occur occasionally while the bubbles rise.