In order to evaluate the effects of nitrogen fertilizer on yield and nitrogen use efficiency for realizing the rationaluse of fertilizer,the experiment was conducted to study the effects ofnitrogen amount and ratios onyield,dry matter accumulation and nitrogen use efficiency in winter wheat-summer maize rotation system in Yuncheng,South Shanxi Province.Three total nitrogen amounts(300,450 and 600 kg/hm 2)and three nitrogen distribution ratios in winter wheat and summermaize(4∶6,5∶5 and 6∶4)were used in 2015 tO₂017.Highest yield were gained at 450 kg/hm 2 for winter wheat andsummer maize in their single growth seasons,and excess nitrogen decreased grainweight.The highest total yields in the year was gained at 450 kg/hm2with 5∶5 nitrogen distribution ratio between winter wheat and summermaize.Dry matters andtotal nitrogen absorptionincreased,and nitrogen useefficiency,nitrogen absorptionefficiency,nitrogen harvest index andnitrogen partial factor productivity decreased with nitrogenincrease.The highest nitrogen use efficiency was gained at 450 kg/hm2with 5∶5 or 6∶4 nitrogen distribution ratio between winter wheat and summermaize.It is suggested applying N 450 kg/hm2 with 5∶5 nitrogen distribution ratio between winter wheat and summer maize would gain the highest yield and higher nitrogen use ef ficiency.