Abstract: 【Objective】To explore the changes of photosynthetic characteristics and yield of maize under straw returning and nitrogen fertilizer application in the wind-sandy loess region of Inner Mongolia.【Methods】Compared and analyzed the effects of maize leaf area index（LAI）,photosynthetic characteristics and yield under five different treatments：nitrogen used to apply （FN,CK）,habitual application of nitrogen combined with straw returning （FNS）,high application of nitrogen combined with straw returning（HNS） ,nitrogen reducing topdressing proportion to basal（RN）,nitrogen reducing topdressing proportion to basal combined with straw returning （RNS）.【Results】The order of leaf area index under different treatments was RNS>HNS>FNS>FN>RN,net photosynthetic rate of FNS,HNS and RNS treated with returning to the field increased by 20.21%-20.49%,21.69%-24.49%,25.50%-36.51%;transpiration rate increased by 10.64%-16.13%,13.83%-18.98%,18.62%-20.30%;stomatal conductance increased by 11.50%-12.93%,14.95%-22.43%,18.65%-22.93%;intercellular CO₂ concentration increased by 12.30%-14.59%,20.31%-20.47%,17.08%-34.49%;photosynthetic water use efficiency increased by 6.72%-9.87%,10.89%-12.50%,12.89%-13.38% compared with the control FN（CK） without returning to the field.There was no significant difference in VPD among the treatments （P>0.05）.There was no significant difference between RN and FN（CK） treatments without returning farmland.The overall photosynthetic index was straw returning to field > straw not returning to field.In terms of yield,the yield of RN treatment was lower than that of FN（CK） treatment,but did not reach a significant level（P>0.05）;compared with the control FN,the grain yield of maize treated with FNS,HNS and RNS increased by 5.30%,10.93% and 11.41% respectively,and the stem yield increased by 8.55%,13.80% and 10.55%,respectively;the yield of maize after straw returning to the field with additional nitrogen fertilizer and nitrogen fertilizer was better than that of conventional nitrogen fertilizer application.【Conclusion】Compared with single nitrogen fertilizer,straw returning combined with nitrogen fertilizer could significantly improve the photosynthetic characteristics and crop yield of maize（P<0.05）,especially the forward transfer of nitrogen fertilizer combined with straw returning was the best.Recommending nitrogen fertilizer combined with straw returning was a cultivation mode of saving cost,stable yield and efficiency on maize in the wind-sandy loess region of Inner Mongolia.

Key words: Straw returning, Nitrogen application, Nitrogen fertilizer topdressing earlier, Maize, Photosynthetic characteristics, Yield