The large eddy simulation (LES) has accurate calculation, but consumes a lot of computer resources. Based on the WRFV3.7 model with four to five nested domains, a radiation fog in North China is simulated through the dynamic downscaling method, to retain the advantages of the LES and reduce the computational time. The results show that, compared with LES scheme under the same horizontal grid resolution, dynamic downscaling method can predict formation of fog more successfully, and in addition, save 47.02% to 67.67% computational time. This study raise possibility for the LES scheme to be used in the operational forecast system in the future.