Abstract: After a comparative analysis on the soil investigation data of North China Plain in the 20th century, the changes of soil fertility in the process of agriculture practices changing from traditional agriculture to modern agriculture have been expounded. The results of the analysis show that the soil fertility has been increased in northern Hebei and decreased in southern Hebei and northwestern Shandong. The factors affecting soil fertility are: river harnessing, fertilizer application, and the changes in cropping system and land utilization after the adoption of high yield hybrid verities.