To provide a basis for the effective utilization of fertilizer in the growth and production ofquinoa，the effect ofdifferent amount of nitrogen(N)fertilizer and different base to topdressing ratio on the root morphological characteristics，physiological metabolism，agronomic trait as well as tuber weight of quinoa were studied under drip irrigation mode. Theresults showedthat，with 2∶1 base to dressingratio，60 kg/hm²N fertilizer application improved the rootvigor，the production rate of O₂ ?-and MDA content were significantly lower than that of control(C1)，while the MDA content peaked under 90 kg/hm²N fertilizerapplication，SOD activity reduced with a reactive oxygen metabolism disorder. As awhole， under the condition of 60 kg/hm²N fertilizerapplication，the accumulation of reactive oxygen was relatively low. High levelof N fertilizer(60 and 90 kg/hm²)with low ratio of N topdressing promoted the extension of quinoa root system. The total root length and root surface area of quinoa under 60 kg/hm² N fertilizer were higher than that of 30 kg/hm². The root diameter and root volume of quinoa under 60 kg/hm² N fertilizer were higher than that of other treatments. The yield and single plant weight of quinoa under 60 kg/hm²N application were higher than other treatments and tuber weight was74.6%，86.8% and 40.3% higherthan the control respectively. Under the same N application amount and 1∶2 base to topdressingratio，the comprehensiveperformance of quinoa plant was the best，with a moderate plantheight，relatively thick stalk and largest plant weight. Inconclusion，a moderate amount of N fertilizer application(60 kg/hm²)along with an appropriate ratio of topdressing fertilizer applying during quinoa fertility stage could alleviate the osmotic stress caused by imbalance between the concentration of soilsolution and the infiltration potential of root cells through the adjustment in physiological metabolism and root morphology，consequently，reduce the degree of lipid peroxidation and cell membrane damage of quinoa rootsystem，improve the plant growth and development. With 60 kg/hm²N application amount and 1∶2 base to topdressingratio，the comprehensive economic characters were the best.