Abstract: The effects of sodium bisulfite（NaHSO3）on nitrate reduction and photosynthetic capacity were studied in the leaves of non-heading Chinese cabbage. It had been investigated the impact of 0（control），2（S2），5（S5），10（S10）and 15（S15）mmol · L^-1 NaHSO3 concentrations on plant biomass，nitrate content，nitrate reductive（NR）activity and photosynthetic capacity after spraying for 0，4，8，12，16 d in the 5 leaves stage of non-heading Chinese cabbage seedling. With the application of different NaHSO3 concentrations，the significant concentration effect and time effect were observed on
plant biomass，NO₃^-  content and NR activity in the leaves. However，the most significant effect was presented for the 12th day of S10 treatment comparing with control，in which not only did the NO₃^- contentdecrease by 44.85% and NR activity increase by 51.26%，but also the plant height and shoot dry weight
distinctly increase. Moreover，the NaHSO3 dramatically increased net photosynthetic rate（P_n），carboxylation efficiency（CE），maximal carboxylation rate（V_cmax），primary quantum efficiency of PSⅡ（Q）and maximal electron transport rate（ETR_max）in leaves. Thereby，the NaHSO₃ stimulated NR activity firstly，then drove assimilation of nitrate，and reduced nitrate accumulation finally；On the other hand， the positive action of NaHSO3 for anabolic metabolism of nitrogen was triggered by more production of carbon skeleton and energy supply mainly due to promotion of photosynthetic carbon assimilation efficiency，which improved by the increase of PSⅡ electronic transmission ability and carboxylation reaction rate.