Insufficient irrigation water resources and excessive input of nitrogen fertilizer are very common in agricultural production in North China Plain. In order to deal with these problems, a field trial with winter wheat as test material was conducted in the lysimeters in 2018—2019. Under three irrigation levels of W1 (60%ETc(reference crop water requirement), 300mm), W2 (75%ETc, 370mm) and W3 〖JP3〗(ETc, 495mm), and three nitrogen levels of N1 (180kg/hm2), N2 (255kg/hm2) and N3 (330kg/hm2), the effects of irrigation-fertilization methods on soil water and nitrogen distribution, photosynthetic characteristics and light response curve parameters of winter wheat flag leaf function period and wheat grain yield were examined. The results showed that W2N2 treatment can maintain wheat growth demand and improve water and nitrogen use efficiency, which increased soil water storage by 41.12mm and decreased soil nitrate leaching by 15.87%, compared with that of W3N3 treatment. The interaction of water and nitrogen had a significant effect on the photosynthetic characteristics of wheat flag leaves. The Pn, Tr and Gs of W2 and W3 treatments was significantly higher than that of W1 treatment, but there was no significant difference between them, and N treatment had the same response. According to the result of yield test, W2N2 had the largest yield, with significant difference than other treatments. In addition, there was a significant relationship between yield and photosynthetic characteristics, light response curve parameters, which indicated that the improvement of photosynthetic characteristics caused by water and nitrogen was conducive to the accumulation of photosynthetic products, and then increased the yield. Under the conditions of this experiment, W2 treatment (irrigated 370mm in overwintering period, 75%ETc）combined with N2 treatment (with nitrogen application rate of 255kg/hm2) can not only maintain high photosynthetic characteristics and crop yield, but also improve the utilization of soil water storage and reduce the risk of nitrate leaching, realizing the water-saving and nitrogen reduction production of winter wheat in the North China Plain.