To explore the effect of different nitrogen reductions on the yield and photosynthetic characteristics of mechanical transplanting hybrid indica rice，and to provide a theoretical basis for reasonable nitrogen reduction in rice，based on the most high yield nitrogen application rate(180 kg/hm²，N180)，field experiment with three kinds of nitrogen reduction(N150:1/6 of nitrogen reduction；N120:1/3 of nitrogen reduction；N0:without nitrogen application) were conducted to study the tiller dynamic，leaf area index，photosynthetic potential，grain-leaf ratio，dry matter accumulation and translocation，yield and its components of hybrid indica rice with Yixiangyou 2115 and Fyou 498 as materials.The results showed that:(1) Compared with the N180 treatment，the yields of two rice varieties in N150，N120 and N0 conditions were decreased by 3.09%，9.04% and 34.37%，respectively.Compared with N180，the effective panicle number and grains per panicle of rice in N150 were decreased by 7.57% and 0.81%，respectively，and the seed-setting rate and 1000-grain weight were increased by 1.98% and 0.87% respectively.The seed-setting rate and 1000-grain weight of rice in N120 increased，but the effective panicle number and grains per panicle decreased significantly.(2) Compared with N180，the number of tillers，leaf area index，dry matter accumulation，and photosynthetic potential and population growth rate of rice at the main stage in the three nitrogen reduction conditions showed a continuous decrease.The leaf area index of rice at heading stage in N150 was not significantly decreased as compared with N180，but the high-efficiency leaf area ratio increased by 4.58%，the grain-leaf ratio increased，the dry matter accumulation rate from heading to maturity increased by 4.11%，the dry matter transfer rate and conversion rate increased by 13.82% and 6.89%，respectively，which resulted in a higher yield in N150.Therefore，the appropriate nitrogen reduction for hybrid indica rice could improve the group photosynthetic structure，promote dry matter accumulation and transport after heading and maintain a high yield level，while excessive nitrogen reduction caused a significant reduction in group growth which was difficult to achieve high yield.