This study adopted two factors split plot design to study effects of the wheat/rape straw returned and nitrogen management of direct seeding on rice photosynthetic characteristics, the influence of the dry matter accumulation and yield. The main area was wheat /rape straw turned over and returned to the field(M1) and the straw was not returned to the field (M0). In the secondary area, 4 nitrogen fertilizer management contained the control with no nitrogen application (N0), three groups with the ratio of the application rates of basal fertilizer, tillering fertilizer, flower-promoting fertilizer and flower-protecting fertilizer was 1∶0∶0∶0 (N1), 3∶3∶2∶2 (N2), 2∶2∶3∶3 (N3), respectively. The results showed that under wheat-rice or rape-rice rotation, nitrogen fertilizer management had significant or very significant regulation effects on dry matter accumulation, photosynthetic characteristics and yield of direct seeding rice at main growth stages. And straw returning significantly affected leaf area index (LAI) and population dry matter accumulation of rice at jointing stage and full heading stage. Meanwhile, the regulation effect of rape-rice rotation was significantly higher than that of wheat-rice rotation. When straw was not returned to the field, combined with N3 fertilization, it could effectively increase the net photosynthetic rate, SPAD value and leaf area index of flag leaves, delay leaf senescence, and maintain a high population growth rate from jointing stage to mature stage. The advantage of dry matter accumulation is obvious. Under the nitrogen fertilizer management mode of straw returning to the field with N2, the population of direct seeding rice with wheat /rape stubble had reasonable construction, strong photosynthetic capacity of flag leaves at filling stage, more grains per panicle, high yield, and the highest yield could reach 10 090 kg/hm2 and 10 693 kg/hm2. In summary, with wheat /rape-rice rotation, the nitrogen fertilizer management model of straw returning to the field combined with that the ratio of the application rates of base fertilizer, tillering fertilizer, flower promoting fertilizer and flower protection fertilizer was 3∶3∶2∶2 could achieve high and stable yield of direct seeding rice.