This experiment was carried out with the low-nitrogen and high-efficiency inbred lines(PH6WC)，and low-nitrogen and low-efficiency inbred lines(ZY118) to research the effects of N fertilizer on yield，dry matter，N accumulation and enzyme activities related to N metabolism under four N levels i.e.0 kg/hm²(N0)，90 kg/hm²(N90)，180 kg/hm²(N180) and 360 kg/hm²(N360).The results showed that the yield，dry matter accumulation and N accumulation of maize inbred lines increased first and then decreased with the increase of N application level，the yield，plant dry matter，N accumulation，enzyme activities related to N metabolism(NR:nitrate reductase；GS:glutamine synthetase，GOGAT:glutamate synthetase) and nitrogen use efficiency(NUE) of high-efficiency type was significantly higher than low-efficiency type，taking yield as an example，the high-efficiency type was 51.99%，46.27%，32.43% and 19.86% higher than those of the low-efficiency type from N0 to N360，respectively，while dry matter transport，dry matter transport contribution rate to grain and N transport were lower than low-efficiency type.The results of correlation analysis showed that the yield，N accumulation and NUE were positively correlated with dry matter and enzyme activities of GS and GOGAT.The dry matter accumulation and enzyme activities of GS and GOGAT can be used as the screening indexes of maize with high NUE.In conclusion，high-efficiency maize inbred lines(PH6WC) had higher yield，dry material accumulation，N accumulation and activities of enzymes involved in N metabolism under different N treatments，which can reach stable and high yield at low N level.