The application of chemical fertilizer plays an important role in the guarantee of world food security.The long-term experiment reveals the characteristics of soil fertility and the law of nutrient balance. Combining witha large number of long-term research materials, progresses of researches on the growth and decline of soil organicmatter and the influence of components’ variation caused by long-term application of chemical fertilizer were sum-marized in the paper. The influence of applying N P K separately or together on soil fertility was further explained.This will provide reference to maintain and improve the soil fertility of farmland ecosystem, as well as theoreticalsupport for rational application of fertilizer.