Based on sandstorm data documented by 311 meteorological stations from 1961 to 2003, the source, moving direction and abruptly changed characteristics of sandstorm in Northwest China were analyzed with CEOF method. The results show that ①the spatial phase and amplitude function of primary compound major component that expanded from the temporal variation fields of sandstorm days and duration by CEOF have close relation with the source of sandstorm, and there is also a close relation between the early phase center of phase function and major desert areas of northern China, and by comparison, the expanded elements of temporal variation CEOF of sandstorm duration has rich information; ②the sandstorm days in Northwest China decreased generally in recent 43 years, and in the first 17 years there was larger fluctuation amplitude but without remarkable decrease trend, it is the high frequency period of sandstorms, and in the next 26 years sandstorm days showed a decreasing trend year by year, the abruptly falling phase was in 1977—1978; ③the temporal series phase of the second compound major component kept positive before 1977 and changed to negative after 1978, the temporal amplitude of the second compound major component was higher before 1975 and lower after 1976, the period of sandstorm frequency changed from more into less was in 1977—1978.