The dynamic of farmla nd soil carbon is a research focus in carbon cycle of the terrestrial ecosystem. Clarifying the dominant pathway and factors of soil carbon fixation as well as emissions under human intervention would provide the theoretical foundation for improving soil quality and soil productivity, developing farmland carbon reduction measures and mitigating global climate change. This research clarified the carbon cycling of farmland soil, discussed the carbon dioxide emission and cycle characteristics, in order to make theoretical foundation for farmland management measures about soil carbon emission reduction and carbon sequestration in northeast Black Soil. In Qing-gang County of Heilongjiang Province at the typical area of Black Soil, this research took different cultivation measures and two ways of corn straw application, including deep scarification at 25 cm soil depth (T1), deep scarification at 25 cm soil depth combined with straw crushed and buried in farmland (T2), deep scarification at 35 cm soil depth (T3), deep scarification at 35 cm soil depth combined with straw crushed and buried in soil (T4), deep scarification at 35cm soil depth combined with straw crushed and mulching on surface (T5), analyzed and determined the accumulated emissions of soil carbon, soil respiration, soil temperature, soil moisture content, soil active organic carbon fraction and crop yield in the 5 treatments. Results showed that straw crushed and buried in soil improved soil respiration rate, and increased the contents of SOC and soil active organic carbon fractions. The effect of straw crushed and buried in soil was better than that of straw mulching on increasing soil active organic carbon fraction and crop production at soil surface.