This paper statistically analyzed the data of gale and duststorms from 1960 to 2004 observed at the six weather stations in Zhangye City in central Hexi Corridor during the past 45 years,then analyzed in detail the space-time distribution and forming cause of gale and duststorm weather,and has concluded their formative atmospheric circulation situation characteristics and influencing system.

The concept of threshold wind speed for sandstorm and a method to calculate the threshold wind speed with the mean wind speed and duration time of the sandstorm were put forward in this paper.