In order to explore the factors that affect the phase transition response time of VO2 thin films irradiated by pulse laser, we simulated the irradiation process based on COMSOL. The physical model of irradiation VO2 thin films was established first, and the boundary conditions of the model were set, the infrared pulse laser irradiated three groups of VO2 thin films prepared by molecular beam epitaxy, and the average absorptivity of the film was obtained indirectly, the absorptivity experimental data was brought into the calculation model. The influence of laser power density, substrate thickness and initial temperature of VO2 thin films on the simulation results were considered in the simulation. Experimental results show that: increasing the laser power density and initial temperature, decreasing the base thickness can shorten the phase transition time of the film irradiation center. What′s more, the phase transition time and the laser power density show exponential decay trend. The 5 000 W/mm2 laser irradiated three groups of VO2 thin films, respectively, their base thickness are 0.15 mm, 0.3 mm, 0.5 mm, the time of phase change is 157 ns, 250 ns and 455 ns respectively. The phase transition time decreases linearly with the initial temperature of the film. When the incident laser power level is not specified, we can apply a bias temperature which is close to the phase transition point on the VO2 film, and control the film substrate thickness to shorten the phase transition time. This study has certain guiding significance for the study of phase change response time in the VO2 thin films defensing laser jamming.