Water shortage is one of the major problems in wheat (Triticum aestivum L.) production in northern plain in China.Water-saving technique is most important in wheat cultivation.In this study,we adopted water-controlled irrigation based on measuring soil moisture to improve the fixed-amount irrigation strategy in previous studies.Using wheat cultivar Jimai 22,we measured the photosynthetic performance of flag leaf and dry matter accumulation and distribution in plant under two plant densities and three irrigation treatments.In the 2008-2009 growing season,the plant densities were 150 (M1) and 225 (M2) seedlings per square meter,and the irrigation treatments were designed as relative soil moisture (SM) of 65% at jointing and 60% at anthesis (W0),SM of 75% at jointing and 75% at anthesis (W1),and SM of 75% at 7 d after jointing and 75% at 7 d after anthesis (W2).In the 2009-2010 growing season,only one plant density (M1) was adopted,which showed better performance in yield and water use efficiency (WUE) in the 2008-2009 growing season.Besides,the irrigation treatments were adjusted to SM of 75% at jointing and of 60% at anthesis (W'0),SM of 85% at jointing and 75% at anthesis (W'1),and SM of 85% at 7 d after jointing and SM 75% at 7 d after anthesis (W'2).Under the same irrigation treatment,maximal photochemical efficiency of PSⅡ (Fv/Fm) and actual photochemical efficiency of PSⅡ (Φ PSⅡ) under M1 density were higher than those under M2 density from middle to late grain-filling stage,and dry matter accumulation amount after anthesis and dry matter translocation amount to grains in M1 treatment were significantly higher than those in M2 treatment.Compared with W1 treatment,Fv/Fm and ΦPSⅡ of W2 treatment were significantly higher from middle to late grain-filling stage,and photosynthetic rate (Pn),evapotranspiration (Tr),leaf water use efficiency (WUE L),and stomatal conductance (Gs) were also higher in W'2.Under the M1 plant density,the dry matter accumulation amount after anthesis and its contribution to grains were higher in W2 than in W1 treatment,whereas the grain yield and WUE of W2 treatment were significantly higher than those in W1 treatment.The changing tendency of dry matter accumulation and distribution,grain yield,and WUE were similar in both growing seasons.In wheat growing environment similar to the condition of this experiment,we propose the best plant density is 150 seedlings per square meter and the best irrigating both at jointing and anthesis is SM (0-140 cm soil layer) of 75% at 7 d after both stages.