Based upon the regional sandstorm records in Cransu，the geopotential height，temperature and wind fields at mandatory levels generated by NCEP/ NCAR reanalysis dataset(2. 50 X2. 50Lat/Lon) for 46 years(1955一2000)，The 5 active sandstorm years and the 5 inactive sandstorm years in spring over Cransu are selected respectively to contrast the difference on the large一scale atmospheric circulation and the relevant即namical and thermo即namic factors.  The results show that the climatic circulation bac掩rounds between more and less spring sandstorm in Cransu are evidently different.  Therefore，it is revealed the facts that the anomalies of the largescale circulation and the relevant勿namic and thermodynamic factors can result in the formation of firing sandstorm in Cransu.  So that the climatic causes of sandstorm in Northwest China can be understood very well. Abovepreliminary results have some novel and applied value for the climatic prediction of the sandstorm in Northwest China.