Aerobic composting of reed straw with exogenous nitrogen addition is an important way to utilize reed resources. The greenhouse gas emissions and carbon and nitrogen losses of aerobic straw composting are mainly affected by the type of nitrogenous substrate，substrate carbon and nitrogen ratio and additional inputs. In order to investigate the effects of different nitrogen sources on greenhouse gas emissions and carbon and nitrogen losses during aerobic composting of reed，a 40 d aerobic composting test was carried out with reed as the raw material，and two treatments were set up:addition of urea and addition of ryegrass，and the static box-gas chromatography was used to determine the concentrations of CO₂，CH4 and N2O，and the traditional chemical analysis was also utilized to determine the physicochemical Indicators. The results showed that:(1)The carbon loss in the urea treatment and ryegrass treatment accounted for 46.85%-47.03% and 46.62%-46.78% of the initial total carbon，respectively；the nitrogen loss accounted for 9.81%-13.23% and 8.92%-10.62% of the initial total nitrogen，respectively. CO₂-C loss in the ryegrass treatment was significantly increased by 5.41%-8.38%，compared to the urea treatment；Neither treatment accounted for more than 0.01% of the total carbon loss with CH4-C loss；N2O-N loss in the urea treatment was significantly increased by 24.11%-30.93%，compared to the ryegrass treatment. The NH₃-N loss of urea treatment was significantly increased by 10.42%-27.63% than that of ryegrass treatment.(2)Physicochemical indicators were correlated with the emission fluxes of CO₂，CH4，N2O and NH₃. Temperature and total organic carbon were positively correlated with CO₂，CH4 and NH₃ emissions；C/N was positively correlated with CO₂ and CH4 emissions；NO^3--N was negatively correlated with CO₂ and CH4 emissions，but significantly positively correlated with N2O emissions. The results of redundancy analysis showed that NO^3--N and C/N had the greatest influence on CO₂，CH4，N2O and NH₃ emissions.(3)Regardless of the model，the cumulative emissions of the three Greenhouse Gases were the largest for CO₂ and the smallest for CH4.(4)The emission characteristics of greenhouse gases and NH₃ from different nitrogen sources were different. The addition of ryegrass increased the cumulative emissions of CO₂ and CH4 by 9.64% and 0.23%，respectively，decreased the cumulative emissions of N2O by 28.76%，and increased the total greenhouse gas emission equivalent by 48.48 kg·t-1. The study showed that the ryegrass treatment had smaller carbon loss and nitrogen loss，and the urea treatment was more effective in terms of total greenhouse gas emission reduction. Combined with the seed germination index of the two treatments，ryegrass was recommended as a nitrogen source with reed aerobic composting.