Abstract: Based on the investigation of typical sampling sites in the alluvial plain of the Haihe River,a functional equation,covering standard grains and natural quality of corresponding farmland,etc.,was established and used to calculate theoretic productivity. By referring to the data of actual grain output in the 3 years (2003—2005). Grain yield-increasing potential,land use intensity and management advantage of these farmland were analyzed. Results show that the gross theoretical productivity of the farmland in the Haihe River alluvial plain area was 3.03×10⁷ t,much higher than the actual output,1.49×10⁷ t on average in the three years 2003-2005. Currently,farmland resources for grain security is highly guaranteed. Through analysis of management advantage,the farmlands are sorted into different grades. Farmlands high in management advantage are concentrated in the alluvial plain area in Central South Hebei Province,where the grain productivity is under-developed due to limitation in irrigation facilities and other farmland infrastructures,and management level. So there is much room for the farmlands therein to increase grain output.

Key words: theoretical productivity, standard plot, grain yield, alluvial plain area of Haihe River