Abstract: we designed different treatments of different seeding density(seeding quantity) to study the yield component and the state of growing with the variety Longjing9 under the same fertilizer conditions .In the experiment, we measured the quality of seedlings, dynamic leaf area of post transplanting, and dry matter of plant from sowing seeds to harvest . The Result is as follows: specified leaf weight, dry matter of plant, and dry and fresh weigh of panicle would descend accompanying to the increasing of amount of sowing; the panicle number per m2of yield component: 3seeds＞2seeds＞1 seed; seed number per panicle: 1 seed＞2seeds＞3seeds; the percentage of ripe grain and 1000grain weight would decline with the increasing of grain number. In all, reducing the seeding quantities is a valid way to enhance the yield of rice.