In order to reveal the influence of irrigation methods and nitrogen fertilizer on characteristics of functional leaf's photosynthetic light response of direct-seeding rice in cold and black soil region, the test-pit experiments was carried out Two factors were set, including irrigation methods and nitrogen fertilizers. The characteristics of photosynthetic light curve of rice leaf with different water and nitrogen regulations in the tillering stage and the heading-and-flowering stage was studied by using comprehensive test design. The result showed that when nitrogen rate increased, photosynthetic light response curves of direct-seeding leaf rised, especially when the photosynthetic photon flux density was higher than 600 μmol/(m²·s). Parameters derived from non-rectangular hyperbola model indicated P_nmax (maximum photosynthesis rate), α (apparent quantum yield) and LSP (light saturation points) increased with the increase of the nitrogen rate, while LCP (light compensation points) reduced. P_nmax, α and LSP of controlled irrigation treatments were higher than those of flood irrigation treatments at the same nitrogen rate, while LCP was lower. In conclusion, higher nitrogen inputs, within the range of 0~135 kg/hm², and controlled irrigation method lead to the increase of photosynthetic capacity, enhancing the light use efficiency and the adaptability to both strong and weak light of rice leaf. These findings were helpful for improvement of photosynthetic light response curve and rice yield. It should be taken into full consideration for the effects different nitrogen levels and irrigation ways on leaf's photosynthetic light response curve in paddy of direct-seeding rice.