In this paper

a quantitative research on the relationship between strong wind aays and sand-dust storm days has been made by using 40 years meteorological data of five types of underlying surface in northern China

which includefarmland

grassland

sandland

gobi and salt crust. By analyzing

we can find that there are certain correlations between the days of sand-dust storm and strong wind for different types of underlying surface. Underlying surface has great influence on sand-dust storm

but there are pronounced differences in different types of underlying surface for this influence. The sand-dust storm days of grassland

gobi and salt crust

with smaller interannual variation are obviously less than strong wind days. On the other hand

the sand-dust storm days of farmland and sandland increase evidently

even in many years

are much more than strong wind days. The differences are mainly induced by the influencing mechanism of different underlying surface on sand-dust storm.