In order to reveal the effects of aged biochar on greenhouse gas emissions and maize growth under different irrigation amounts and water salinities, two biochar addition rates: 0t/hm2（B0）, 60t/hm2（B1）, two irrigation water salinities: 0.71g/L（S0） and 4.0g/L（S1）, and two irrigation levels of full irrigation (W1) and deficit irrigation （W2，1/2 W1) were set and the field experiment of spring corn was conducted at the National Field Scientific Observation and Research Station on Efficient Water Use of Oasis Agriculture in Wuwei of Gansu Province from April to September 2022. The results showed that the cumulative CO2 emission of deficit irrigation was decreased by 24.13%~52.68% compared with that of full irrigation. However, there was no significant difference in N2O emissions between the two irrigation levels. The cumulative emissions of CO2 and N2O were increased by 9.06%~24.79% and 9.95%~18.03% respectively, due to brackish water irrigation. Under the four irrigation treatments, aged biochar decreased the accumulated emissions of CO2 and N2O by 7.33%~18.78% and 21.14%~29.76%, respectively. There was no significant impact on CH4 emissions among different treatments. Deficit and brackish water irrigation inhibited the growth of crops. Aged biochar significantly increased the biomass of spring maize by 7.86%~25.82%, but its effect on the yield of maize under W1S0, W1S1 and W2S0 treatments was not significant, and the yield of maize under W2S1 treatment was significantly reduced. At the same irrigation level, brackish water irrigation increased the global warming potential, while using aged biochar and deficit irrigation reduced it. Brackish water and deficit irrigation significantly reduced soil carbon budget by 17.70%~65.36% and 37.30%~71.96%, respectively. Under different irrigation treatments, aged biochar significantly increased the carbon sink of farmland with a value of 15.86%~33.52%. In general, the application of aged biochar under W1S0, W1S1 and W2S0 treatments had slightly increased the maize yield, significantly reduced the global warming potential and promoted the net carbon income of farmland. Therefore, under these three irrigation methods, the application of aged biochar would increase the local economic and environmental benefits.