Using hybrid millets and their parents as materials,activities of nitrate reductase(NR),glutamine sythetase(GS)and glutamate dehydrogensae(GDH)and nitrogen content in leaves were determined at different growth stages,and the heterosis of the enzymes involved in nitrogen metabolism were analyzed.The study may provide the basis of genetic improvement on nitrogen efficiency.The results showed that GDH activity and nitrogen content of hybrid millet mainly displayed the midparental heterosis at whole growth stag...