Effects of two plant growth regulators G-ABA and S-ABA on activity of nitrate reducates (NR) in leaves of soybean were studied, used varieties Dongnong 163, which was high fat variety, and Dongnong42, which was high protein variety in potted trail. The results showed that activity of nitrate reducates (NR) in leaves showed single peak curve in different treatments, and the influence sequence of G-ABA on activity of NR was as follow: 20 mg/kg＞15 mg/kg＞25 mg/kg＞30 mg/kg＞0 mg/kg＞35 mg/kg, and which of S-ABA was as follow: 35 mg/kg＞30 mg/kg＞25 mg/kg＞20 mg/kg＞0 mg/kg＞40 mg/kg. The activity of NR of different varieties showed higher in middle period and lower in prophase period and anaphase period under different treatments. The effect of PGRs on NR showed that variety of high fat was better than which of high protein.