Abstract: To evaluate the long-term effects of biochar amendment on greenhouse gas emissions (GHGs), a field experiment was conducted to examine the effects of 3-year field-aged biochar (B₃) and fresh biochar (B₀) on global warming potential (GWP) and greenhouse gas intensity (GHGI) of methane (CH₄) and nitrous oxide (N₂O) in a typical rice-wheat rotation system. Four treatments were established as control without nitrogen fertilizer (CK), urea without biochar (N), urea with fresh biochar amended in 2015 (NB₀), and urea with 3-year field-aged biochar amended in 2012 (NB₃). Results showed that both the NB₀ and NB₃ treatments obviously increased soil pH, soil organic carbon (SOC), total nitrogen (TN) and influenced the potential activity of functional microorganisms related to GHGs compared to the N treatment. Relative to the N treatment, the NB₃ treatment significantly improved crop yield by 14.1% while reduced the CH₄ and N₂O emissions by 9.0% and 34.0%, respectively. In addition, the NB₀ treatment significantly improved crop yield by 9.3%, while reduced the N₂O emission by 38.6% though increased the CH₄ emissions by 4.7% relative to the N treatment. Moreover, both the NB₀ and NB₃ treatments could significantly reduce both GWP and GHGI, with NB₃ being more effective in simultaneously mitigating the GHGs emissions and enhancing crop yield. Since field-aged biochar showed obvious effects on GHGs mitigation and carbon sequestration after 3 years, biochar incorporations had long-term effect on GHGs mitigation and crop production in the rice-wheat rotation system.