Abstract: A new sampling solution method of virtual sub-cells technique based on transient adaptive collision distance for collision pair selection was introduced to improve simulation efficiency in DSMC. The new method was validated by comparing standard method’s results with new method’s results of both flat plate and blunt cone aerodynamics under different grid cells. The results show that the cell size constraint of the DSMC method could be relaxed to a limited extent when the cells are supplemented by the virtual subcells, and aerodynamics of flat plate and blunt cone under coarse grid size with this virtual method is consistent with fine grid results.