In order to study the effect of underlying surface near Bohai Sea on gale, sensitivity experiments of terrain and sea surface with two northeasterly gale cases on 13 and 15 April 2009 were conducted using the WRF (Weather Research and Forecasting) model. The results show that the terrain to the north of Bohai Sea may enhance the wind force over the sea, and gale occurs more easterly and cold air moves more slowly. The dynamic block of the northeastern terrain of Bohai Sea may weaken the wind force over the north Yellow Sea. The bell mouthed terrain to the north of Bohai Sea may enhance the wind force to the northeastern part and weaken the wind force to southwestern part. The sea surface may enhance the wind over the sea to 3-5 m·s-1 in the southern part and 2-3 m·s-1 in the northern part, which causes the “shoreward gale” effect. The stronger the wind, the more obvious the ocean effect. In all, the effect of sea surface is stronger than the effect of terrain.