Abstract: This study, based on the Experiment of Straw Return, aimed to examine the effects of different nitrogen application rates on spring maize yield and nitrogen fertilizer utilization efficiency under straw cover, and defined the relationships between spring maize yield and nitrogen fertilizer application rates.In the experiment, straw cover was regarded as main plots and different amounts of nitrogen fertilizer, i.e.0, 135, 180 and 225 kg·hm^-2, were regarded as subplots.The production of spring maize and nitrogen fertilizer utilization efficiency were determined after harvest.The results showed that straw cover decreased plant height(2.71%-6.55%), cob length(4.26%-10.1%), cob diameter(3.92%-7.74%) and 100-grain weight(0.67%-1.68%) in 0, 135 and 180 kg·hm^-2 plots, thus resulting in a decrease of maize yield from 4.30%-11.0%(P<0.05).However, straw cover increased plant height by 6.41%, cob length by 6.38%, cob diameter by 5.67% and 100-grain weight by 4.29% in 225 kg·hm^-2 plots, respectively, thus resulting in an increase of maize yield by 6.82%(P<0.05).Spring maize yield was positively correlated with the nitrogen fertilizer application rate in plots with straw cover, i.e.both yield and yield components increased with the increasing nitrogen fertilizer application rate.With straw cover, both nitrogen agronomy use efficiency and nitrogen partial factor productivity decreased with the increasing nitrogen application rate, indicating that the enhancing effect on maize yield and nitrogen utilization efficiency brought by straw cover was associated with nitrogen application rate.Among the 4 nitrogen fertilizer application rates, 225 kg·hm^-2 combined with straw cover was the most practical way in agriculture practice.