Based on the counties’statistic data in 2000-2003,this paper reveals new regional distribution and difference of food shortage in China in early 21st century.Considering impacts of climatic fluctuation and natural disasters,two types of food-shortage region are given out.One is the food-shortage region in average year that the per capita grain yield is lower than 300kg.Another is the potential food-shortage region that the per capita grain yield is lower than 430kg in average year,which would be lower than 300kg once grain yield is reduced 30% for natural disasters.In order to analyze main reasons of food-shortage and influential factors of grain supply-demand,two types of food-shortage regions are grouped into some sub-types by k-means cluster respectively.The main conclusions are as follows.(1) There are 583 food-shortage counties,about 28% of total 2075 counties and cities at county level in China,and 698 potential food-shortage counties,about 33.6% of total.The food-shortage regions in average year are mainly distributed in the planting area and semi-pasture area west to the sideline of population density near Heihe City in Heilongjiang Province to Tengchong City in Yunnan Province,namely Huhuanyong Sideline of population geography in China.On the contrary,the potential food-shortage regions are distributed widely in the area eastward to Huhuanyong Sideline.(2) Food-shortage regions in average year in China concentrate on the semi-humid and semi-arid area and the area southern to the Changjiang(Yangtze) River.The first area has the largest numbers,covers the widest range,and ranks the 2nd of population and quantity of food shortage.The second area,mostly located in hill area,has the largest population and quantity of food shortage.(3) In the semi-arid and semi-humid transitional zone,the distribution of food-shortage region in average year is dominated,and there are different sub-types of potential food-shortage region as well.More attention should be paid to this transitional zone,for that,in this region,grain security is strongly impacted by the environmental changes,conflicts among population,grain,cultivated land,economic development and environmental protection are distinct.(4) There are diverse reasons of food shortage and distinct regional disparity in food shortage region.Lake of cultivated land is the common and main factors to limit above food shortage regions to improving the self-support of grain.In the semi-humid and semi-arid area,poor natural conditions and lower grain yield per grain-sown area are another important limiting factors.In South China,the self-support of grain is influenced by comparative dominance of crops,and proportion of grain-sown area is lower.Therefore,it is very important to safeguard strictly basic cultivated land in China.At the same time,decrease trend of grain-sown area should be controlled strictly in South China and traditional grain-output region in North China.