In order to investigate methane(CH_4) and nitrous oxide(N_2O) emission fluxes under different straw returning patterns, an 8-year field trial in Suzhou, typical rice-wheat double cropping region in southern area of Jiangsu province, was conducted using static chamber-gas chromatograph technique in situ. Straw returning patterns were rice straw returning (R), wheat straw returning (W), both rice straw and wheat straw returning (RW) and no straw returning treatment (CK). The results showed that total CH_4 and N_2O emissions in straw returning treatments were significantly (P<0.05) higher than those in CK treatment, but the changes between the three straw returning patterns were not distinct. Total CH_4 emissions under different treatments followed the order of R>RW>W>CK, while W>R>RW>CK for the total N_2O emission during the whole wheat-growing season. Global warming potentials (GWPs) for treatments of R, W and RW were 1 225.5 kg/hm~2,CO_2-eq, 1 250.9 kg/hm~2,CO_2-eq and 1 214.5 kg/hm~2,CO_2-eq, respectively, which were significantly (P<0.05) higher than that of CK treatment [1 068.5 kg/hm~2,CO_2-eq]. The yield-scaled GWPs between treatments followed the order of RW>W>R>CK, showing that both rice straw and wheat straw returning pattern had the most significant impact on climate change during wheat-growing season. The contribution rates of N_2O to GWPs were more than 95% for all straw returning treatments, indicating that N_2O was the main objection for greenhouse gas reductions during wheat-growing season. Given that R treatment had the least GWP, rice straw returning pattern should be recommended for one-season straw returning application.