[Objective] The reason of the high level of agricultural fertilization was studied from economics angle.[Method] Farmers fertilization input model was developed.The time series data from 1990 to 2004 in Jiangsu Province was applied for analysis.[Result] The fertilizer price,labor price and agricultural products price can explain 93% of the changes of farmers＇ fertilization level.The influence of farmers＇ education level was insignificant.The dysfunction of the agricultural technology promotion system had certain influence on farmers＇ fertilizing behavior.[Conclusion] The high level of fertilization was partially because of shortage of scientific fertilizing technology and more importantly was the substitution effect caused by the rising in wages of labor in relative to price of chemical fertilizations and the derivation effect caused by the increase in the prices of agricultural products.
