Abstract: An explicit simulation with a fine grid domain at the intervals of 6km is used to explore the inner-core structures of Vongfong(2002). The dynamics for Vongfong strengthening inshore are examined. It is found as follows. (1) The radius of maximum wind of the axisymmetric structures of the typhoon decreases with height during its mature stage. When Vongfong is inshore,the strongest low-layer inflow locates in the front and the outflow is in the rear,which are just the reverse from the Atlantic hurricanes and other Pacific typhoons. (2) The dynamic and energetic fields are highly asymmetric in structure. Convection is stronger in the northwest of the typhoon than in the southeast; the strongest convective cloud bands are consistent with the maximum wind region. During its strengthening stage,it is cold west of and warm east of the typhoon center in the lower layer but warm in the west and cold in the east in the mid-upper layer. During its mature stage,there are evidently warm-core structures in the lower and mid-upper layer. (3) The interactions between mid-latitude cold lows in the middle-upper troposphere and typhoons are the cause for the typhoon to strengthen inshore. Firstly,the outer circulation of the cold low enters into the typhoon in middle troposphere when an outer cold airflow from the cold low flows into the northwest of the typhoon so that geopotentially instable energy increases and convection develops. Secondly,downdraft in the cold low contributes just as the secondary circulation of the typhoon system so that the cold low weakens while moving south and the typhoon strengthens inshore. Due to the CISK mechanics. these two factors might help strengthen the typhoon.