Abstract: In order to provide technical support for Anhui provincial single cropping rice production, the effects of different sowing density and seedling age on yield formation and the number of population under water-raised seedling conditions were researched by using “Xinliangyou 6”. At the same time, the effects of different numbers of basic seedlings and methods of nurturing the seedlings on yield formation and the number of population are researched under the same long seedling age conditions. The results show that seedling age should not exceed 40 days, and 45 days or longer seedling age will result in yield reduction under water-raised seedling conditions. With the seedling age extended, the reduction range will increase; compared with normal sowing density, the reduction is mainly due to seedling age under sparsely seeding conditions. With the extension of seedling age, the population total tillers, LAI, the number of the spike per hm2, the number of grains per spike and seed-setting rate decrease while the difference of population tillers PTP’s changes little. Under the long seedling age conditions, by means of increasing the number of basic seedlings or using fertilized dry land bed way to nurture long age-tiller strong seedlings is an important way to get ideal yield.