The breakup of drop covered with vapor film is numerically simulated. The moving particle semi-implicit method is used to solve the 2-dimensional unsteady Navier-Stokes equations for drop, vapor and ambient fluid. The results show that vapor film suppresses the drop breakup and hence the critical Weber number increases with the increasing thickness of vapor film. The breakup process can be divided into two stages. The drop deformation and breakup mainly occur in the later stage. Three breakup mechanisms are unveiled, which are almost the same as that of drop breakup without vapor film except for the stronger Rayleigh-Taylor instability for drop with vapor film. Our simulation results are comparable with the previous experiments.