The application of chemical fertilizers is an important measure to increase the rice yield，but the effect of long-term application of chemical fertilizers on the soil organic carbon(SOC) content of paddy soil is unclear.Based on the long-term fertilization experiment at the Taoyuan Agro-ecology Experimental Station of the Chinese Academy of Sciences，this paper systematically studied the changes in rice yields and SOC content of different treatments including no fertilization，only N fertilizer application，NP fertilizer application and NPK fertilizer application.The results showed that long-term application of chemical fertilizers increased the SOC content of paddy soil，and the SOC content of balanced fertilization treatment(NPK fertilizer application) was at the relatively highest level；the changes of SOC content was significantly related to the amount of rice stubble residue input in each year.Therefore，the effect of long-term application of chemical fertilizers on the content of SOC mainly depends on the yields benefit.Balanced fertilization will also increase the content of SOC while obtaining high yields.