On the basis of the estimation of the light-temperature potential productivity for different food crops (mainly wheat and corn), this paper according to the maps of the types of agricultural production level and the saline-alkali soil distribution compiled by using the TM satellite images (1:10000), gives corrections of irrigation, soil, fertilizer and agricultural technology level of the high-, middle-, and low-yield land by multihierarchical analysis. It further calculates the potential productivity at each level of different land types and crop potential productivity.This result shows that light-temperature potential productivity is 1470-1580kg/mu; the natural climatic potential productivity is only about 350 kg/mu, and the irrigation climatic potential productivity is clearly enhanced. The restrictive factors of soil and the irrigation condition are the main causes which lead to the complex regional distribution of the land potential productivity. It also shows that economical water utilization, more input of energy and better management are necessary to increase the productivity of the high- and middle-yield land.