Direct simulation Monte Carlo (DSMC) method is currently the most widely used numerical method for rarefied flow calculation. Based on the Fortran programming platform of GPU (Graphics Processing Unit) and CUDA (Compute Unified Device Architecture), the DSMC method was optimized. Taking the calculation of high supersonic aerodynamic heating as an example, the effect of serial and parallel computing speed and simulation molecules on parallel efficiency was studied. The comparison shows that the parallel results are consistent with each other and parallel program achieved an acceleration of 4 to 10 times. And accelerating performance is proportional to the size of calculation. The application of GPU parallel technology will greatly promote the development of DSMC method.