Abstract: Based on the statistical data from 1979 to 2007, this paper analyzed the changes of the total area of arable land, crops, grain and the multiple cropping index(MCI) in the middle and lower reaches of Yangtze River, then calculated the theoretical potential of MCI in each province (municipality) in the middle and lower reaches of Yangtze River by using the model of the quantitative relationship between the maximum of MCI and the heat and water resources. The results showed that the arable land area, grain sown area and yield, the total sown area of crops and MCI decreased in the middle and lower reaches of Yangtze River from 1997 to 2007. By reference to the MCI in 2007, the potential of MCI in the area was 108.37%, Zhejiang was the biggest province in this area whose potential of MCI was 160.5%, followed by Hubei (130.7%), Jiangxi (113.0%) and Shanghai (110.6%), and the potential of MCI of other provinces in this place was big too. The decline of MCI made serious influences on food production. The measures of tapping the potential of multiple cropping indexes in this area, improving the level of agricultural mechanization and making innovations to the land system were worth to be used as reference．

Key words: the middle and lower reaches of Yangtze River, arable land, multiple cropping index, potential