Abstract: As a widespread natural phenomenon in the soil of middle and high latitude as well as high altitude, freezethawing cycles have a great influence on the nitrogen cycle of terrestrial ecosystem in nongrowing season. Freezethawing cycles can alter the physicochemical and biological properties of the soil, which thereby affect the migration and transformation of soil nitrogen. The impacts of freezethawing cycles on key processes of nitrogen cycle in terrestrial ecosystem found in available studies remain inconsistent, the mechanism is still not clear, and the research methods also need to be further explored and innovated. So it is necessary to sum up and analyze the existing achievements in order to better understand the processes of soil nitrogen cycle subjected to freezethawing cycles. This paper reviewed the research progress in China and abroad about the effects and mechanisms of freezethawing cycles on key processes of nitrogen cycle in terrestrial ecosystem, including mineralization, immobilization, nitrification and denitrification, N leakage and gaseous loss, and analyzed the deficiencies of extant research. The possible key research topics that should be urgently paid more attention to in the future were also discussed.