The standardized precipitation index(SPI) was calculated based on monthly precipitation data observed at the nine weather stations in Ningxia Hui Autonomous Region from 1959 to 2011

and the spatial and temporal variation of drought was analyzed using the methods of drought station proportion

drought intensity

climate trending rate and the inverse distance weighted interpolation in ArcGIS. Results showed that annual SPI in Ningxia in recent 53 years decreased with an average rate of-0.131/10 a

which was the largest increase in the 21st century. As for the seasonal change of the SPI

drought in spring

summer and autumn was becoming heavier slightly

while in winter

it was becoming lighter. In view of the scope and drought intensity

the heavy drought expanded slightly in the study area

and yet the light and medium drought declined slightly both in scope and intensity. In the four seasons

drought intensity in winter increased slightly

but its scope shrunk; in spring

both drought intensity and scope increased; and in summer and autumn

drought intensity decreased and its scope shrunk. Continuous seasonal drought occurred from spring to autumn had the greatest impact on agricultural production. Spatial differences of annual and seasonal SPI were obvious. From north to south

drought was gradually aggravated

especially in the southern mountains

the most sensitive to change of regional drought.