Abstract:The dynamics of farmland untrient cycles and balance in the southern part of Jiangsu Province were analysed based on macro-calculation and field tests. The results show that the main nutrient input is changing from organic fertilizer to inorganic fertilizer;farmland internal cycling is being weakened;Nbalance is changing from deficiency to surplus,P from deficiency to equilibrium, while K is becoming more and more deficient. So dnhancing P and K input and limiting N input as well as increasing the return of organic matter to farmland by mechanization are important ways to regulate farmland nutrient balance in this region.