The dust storm is a disastrous weather phenomenon which often occurs in spring in the Northwest of China and is difficult to forecast. Firstly, a synoptic concept model about its happening was developed.According to this model, a numerical forecasting method was designed by means of the calculation of the PBL regimes(stable, mechanically driven turbulence, forced convection and the free-convection regime) and friction velocity.The rationality is shown by a verification on the model with the PSU/NCAR numerical model MM5. Finally, a flowing chart of short-range forecasting method ,which combining the synoptic principle and numerical forecasting technology,was given.