Abstract: Two peanut cultivars,Huayu 22(high yield big peanut) and Baisha 1016(small peanut),were used for investigating the changes of activities of nitrate reductase(NRase),glutamine synthetase(GS) and glutamate dehydrogenase(GDH),and soluble protein contents in different organs.The results showed that the change trends of NRase,GS,GDH and protein contents of two type peanut cultivars were similar.But the protein contents of different organs of Baisha 1016 were higher than those of Huayu 22.The NRase activities of different organs were gradually depressed with growth.The NRase activity of nutlet was higher compared to the other organs.The changes of GS activities in stem and root showed a single peak curve with the peak appeared at grouting stage.The GDH activities in leaves were relatively higher at seedling stage,then reached lowest at pod-pin stage,and increased rapidly afterward.The changes of GDH activities both in stem and root presented a V type curve.The peak GDH in root appeared later that in stem,which was observed at pod-maturing stage.GDH activities in nutlet at mature stage were higher than that of pod-maturing stage.No significant relationships were found between protein contents and the activities of GS and GDH in organs,while protein contents were significant correlated with the NRase activities in corresponding organs.