Cropland is one of the important sources of greenhouse gas(GHG)emissions. Reducing GHG emissions from croplands is of great significance for mitigating global changes. Biochar is the carbon(C)-rich solid material obtained from biomass pyrolysis in an oxygen-limited environment. Due to its high C content, highly porous structure, large specific surface area and considerable recalcitrancy, biochar has become a hotspot in the study of mitigating GHG emissions from croplands. This paper reviewed the recent progresses in the impacts and mechanisms of biochar amendments on GHG(CO_2, CH_4 and N_2O) emissions from croplands as well as the effects of biochar on net global warming potential(NGWP), net greenhouse gas emissions(NGHGE)and greenhouse gas intensity(GHGI). We also proposed further studies on the mitigation of biochar on GHG emissions.