Abstract: The monthly precipitation data from 52 meteorological stations in Inner Mongolia from 1971 to 2015 were used. The methods of M-K test and precipitation anomaly percentage (P_a) were used to analyze the change trend and abrupt change of precipitation, and the spatiotemporal variation of drought at different time scales was also analyzed. The results showed that the inter-annual precipitation variation trend was basically maintained, and two abrupt changes took place in 1998 and 2012 in recent 45 years. Precipitation increased in spring, autumn and winter, but it was opposite in summer. Drought events occurred mainly in winter during the period from 1999 to 2011, and their frequency was the lowest in summer. Spatially, the annual precipitation decreased gradually from the east to the west. The change rate of precipitation was high in the area east of the Greater Khingan Mountains and west Bayan Nur, but it was low in Northwest Hulun Buir, central and southern parts of Tongliao, central part of Chifeng, and western Alxa. In addition, the probability of occurring drought at different levels was in an order of slight drought > extreme drought > moderate drought > severe drought. Drought events occurred generally in west Hulun Buir, Central-North Chifeng, North Tongliao, Central-West Xilin Gol League and West Alxa League. The P_a was in an increase trend in Central-East Hulun Buir, West Bayan Nur and East Alxa League, but it was in a decrease trend from South Hinggan League to Erdos and in Central-West Alxa.

Key words: drought level, precipitation anomaly percentage (Pa), Inner Mongolian