Abstract: In order to reveal trend variation and main economic factors of unit area grain yield in Anhui Province. Based on the grain yield and agricultural economy data in 78 counties and districts of Anhui Province from 1991 to 2010, trend variation and main influential factors of unit area grain yield were analyzed in Anhui Province by adopting varieties of mathematical statistics. The results showed that, during the past 20 years, unit area grain yield of Anhui Province and each county had an obvious increase. During the 20 years, the variation coefficient was large. And the region where the variation coefficient of the decade after and before 2000 increased was also the area where the grain growth rate was low. Using the method of Squared Euclidean distance and Furthest Neighbor and combining with geographical characteristics, the type of unit area grain yield in Anhui could be divided into four parts. There were great differences in variation trend, fluctuation range and yield output level of unit area grain yield. The highest output of unit grain yield was areaⅢ, the value was 5957 kg/hm², and the lowest was areaⅠ, the value was 4255 kg/hm², while areaⅡandⅣwere in the middle, the value were 5089 kg/hm² and 4905 kg/hm². The chief factors that influence unit area grain yield were per capita net income of peasants and governmental expenditure. Then effective irrigation area, total power of agricultural machinery, ensured stable yields despite of drought and flood area and rural electricity consumption were also important factors. Agricultural film and pesticide consumption did not have too much influence. Variation trend of unit area grain yield in each area mainly depended on contribution rate of agriculture economic factors.