[Objective] The aim was to provide a scientific and rational water,nitrogen model for achieving high yield,high quality of wheat and water and fertilizer saving.[Method] Under the field conditions,the effects of irrigation frequencies and N application times on net photosynthetic rate（Pn）,chlorophyll fluorescence parameters of flag leaf and yield of wheat was studied.[Result] The differences on Pn,chlorophyll fluorescence parameters Fv/Fo,Fv/Fm,qP,qN of flag leaves and yield of wheat among different irrigation times had reached a significant level,and the difference between treatment without irrigation and irrigation treatments were relatively large;the difference on Pn,Fv/Fo,Fv/Fm,qP and qN between treatments of basal application of N fertilizer and N application（40%）in returning green stage was not significant,however,the photosynthetic parameters and yield of two treatments were obviously lower than that of N application（40%）in jointing stage or booting stage.[Conclusion] The effects of irrigation frequencies and N application times showed significant interaction effects on photosynthetic characteristics of wheat flag leaves and yield,in which W2N4 treatment combination was best.
