Abstract: Soil organic carbon(SOC) and total nitrogen(TN) are important indicators of soil fertility.Clarifying the impacts of tillage practices and cropping systems on soil carbon and nitrogen levels,thereby crop yields,is beneficial to the enhancements of soil fertility and crop production.A long-term soil conservation experiment was established in Mollisols of Northeast China in 2001.There were four treatments in the experiment,they were:no tillage with continuous corn(NTCC),mouldboard plow with continuous corn(MPCC),no tillage with corn-soybean rotation(NTCS) and mouldboard plow with corn-soybean rotation(MPCS).Under long-term tillage practices combined with crop rotations,the interannual variation of soil carbon and nitrogen contents,and crop yields were investigated.The results showed that with years increasing,NTCC and NTCS treatments significantly increased both SOC and TN contents in 0-10 cm of soil layer; the SOC,TN contents in 10-20cm of soil layer initially decreased and then increased gradually; and the SOC and TN contents in 20-30 cm of soil layer did not change much over time; Compared with the initial storage of carbon and nitrogen in 2001,the carbon and nitrogen storage increased by 20.4% with continuous corn and 18.6% by corn-soybean rotation under the no-tillage treatment,respectively.The NTCC treatment resulted in the highest carbon and nitrogen storage(75.7 and 7.02 Mg·hm^-2).Soil carbon and nitrogen ratio(C/N) decreased gradually over several years of tillage.The lowest average C/N was observed in the NTCC treatment.The NTCS treatment resulted in the highest average yield(10 111 kg·hm^-2) during 16 years,and there was no significant difference among the other three treatments.There were no significant correlations between SOC,TN contents,C/N and corn yields in 0-20 cm of soil layer.The NTCS treatment increased corn yield,and promoted soil carbon and nitrogen sequestration compared with conventional tillage.Further study on enhancing its capacity of carbon and nitrogen sequestration is needed.