Deqing is located in the tropic and subtropic mountain Area of China. Its area of Cultivated land from land use survey is 40% larger than the statistic. Of all cultivated land, owing to the flood, waterlogging, drought and barren soil, the high yield land occupys only 30%, and the mid low yield land 70%, which is far more than the percent statistic. These situations generally existed in tropic and subtropic mountain areas of South China. So the measures to protect the high yield cultivated land strictly, to improve parts of the mid low yield selectively, to adjust agricaltural structure further, and to control soil erosion, are necessary to make best use of its advantages and bypass the disadvantages.