Abstract: In this paper, the Songjing 15,a new super rice variety identified by the Ministry of Agriculture and Rural Affairs, and Songjing 9 were selected as the research object and as the control material respectively, 4 cultivation densities and 5 fertilization levels were set to investigate the agronomic traits including effective panicle number, solid grain number, flat grain number, panicle length and 1 000-grain weight, dry matter mass and leaf area.And, the optimum cultivation conditions and high yield mechanism of Songjing 15 were also discussed.The results showed that Songjing 15 had the highest yield under the cultivation density of 30 cm × 13.2 cm and pure nitrogen application of 13 kg·（667 m~2）^-1.The analysis of dry matter mass and leaf area index（LAI） at different growth stages under different fertility showed that Songjing 15 could maintain high LAI and SPAD values at heading stage and grain filling stage, which greatly increased the dry matter accumulation and laid the foundation for the increase of yield.