Abstract: We use the lattice Boltzmann method （LBM） to study the evolution of phase transition procedure, and reveal the mechanism of negative pressure in the gas-liquid mixing system. Shan-Chen model can be used to simulate the phase transition phenomenon, this model uses a pseudo-potential to represent the interaction between different phases, thereby controlling the separation of different phases, with the help of inter-particle force we can obtain an equation of state like the van der Waals equation of state, then we can determine the critical conditions of phase transition and the generation of negative pressure through the study of the state equation. Using the LBM, it is possible to make the numerical simulation of phase transition and the negative pressure phenomenon, and verifying Laplace＇s law in the gas-liquid mixing system. From the results, we have found that when the droplet is in both force and thermal equilibrium with the surrounding gas, the relationship between the pressure difference and the droplet＇ s radius fits Laplace＇ s law very well. In addition, it generates negative pressure in the gas-liquid interface. To make the theoretical explanation consistent with the results of numerical simulation, we adopt the real van der Waals equation of state and the molecular dynamic method to explain the origin of negative pressure. When the inner pressure is strong enough, the negative pressure will appear. Explaining the generation of inner pressure causes further understanding of the microscopic mechanism of negative pressure.

Key words: lattice Boltzmann method, phase transition, negative pressure, Laplace＇ s law, inner pressure