Based on the surface meteorological observation date from 20 stations in the Beijing area from 1954 to 2002, an investigation is conducted of the temporal and spatial distribution characteristics, especially the long term trend and variation of sand dust storms, and the monthly variation in the Beijing area in recent 48 years. Also analyzed are the characteristics and causes of sand dust storms in Beijing in recent three years. Some variation regularities of sand dust storms are analyzed through wavelet analysis. It is found that there is an extra long period of 12-14 years and a short period of 2-4 years in floating dust days; and there is an extra long period of 8-12 years in fly sand days