There was a ohvious decrease of sand and wind activities during the last tne years in beijing.The average windy days and the sand-driving wind days from 1991 to 1992 were 34% and 21.9% respectively as compared with the multi-year average values before 1980.The reason of decrease of sand-driving wind days was that the sand producted in Beijing area itself decreased because of a better-green-layer above land.But if the greening-work in the upper-reach of wind area delays, it will have aimpact on the sand and wind activities in Beijing.