Rice season is the main period of greenhouse gas emissions in paddy-upland rotation ecosystems,exploring effective measures to reduce greenhouse gas emissions simultaneously improve rice yield has become a hot topic in current research. Integrating rice and duck during rice growth,called rice-duck mutualism,is one of the most effective measures to reduce greenhouse gas emissions,and determining reasonable density of rice-duck mutualism is great significance to reduce greenhouse gas emissions based on stable rice yield in Erhai basin. In order to obtain optimal density,effect of rice-duck mutualism density on greenhouse gas emissions regulation,emission flux and global warming potential (GWP) were analyzed using a closed static chamber-gas chromatography. The results showed that the emission peaks of CH_4 and N_2O appeared at tillering stage and grain-filling period during rice growth. The orders of emission flux,cumulative emissions and total emissions of CH_4 were conventional treatment (CT) > low-density duck treatment (LDD) > high-density duck treatment (HDD) > no chemical fertilizer treatment (CK),and the orders of N_2O were HDD > LDD > CT > CK. Compared with CT,total CH_4 emission of CK,LDD and HDD decreased by 45%,18% and 25%,respectively,total N_2O emission of CK,LDD and HDD reduced by 8%,-11% and - 37%,and GWP was respectively reduced by 41%,14% and 17%. DO,NH+4 -N and NO-3 -N in the surface water and soil temperature were the main factors causing differences in CH_4 and N_2O emissions. The orders of rice yield were LDD>CK>CT>HDD. Reasonable density of rice-duck mutualism reduced CH_4 emission,increased N_2O emission,slowed global warming potential,and improved the rice yield. Considering relative higher rice yield and greenhouse gas emissions reduction,the comprehensive benefit of LDD was the best.