In order to study the impacts of planting density of nutrition bowl seedling mechanical-transplanting rice on photosynthate production and yield, a field experiment was conducted using conventional japonica rice Nanjing 44, Wuyunjing 24, japonica hybrid rice Yongyou 8, Changyou 5, and indica hybrid rice Liangyoupeijiu, II you 084 which have been widely grown in the southern China with high, medium and low density treatments of the different hill spacings in nutrition bowl mechanical-transplanting (12 cm, 14 cm, and 16 cm), and the conventional blanket seedling mechanical- transplanting as control. The results showed that, the tiller number of nutrition bowl mechanical-transplanting rice in the critical period and the declining rate of leaf area after heading decreased with the reduction of planting density, the productive tiller percentage increased significantly, while the chlorophyll content of flag leaf and the photosynthetic parameters presented the opposite trend. The dry matter weight of single stem, the matter transportation amount in stem and leaf, and the net assimilation rate were all the highest in the low density treatment, the medium in medium density treatment, and the lowest in high density treatment. After heading, the dry matter accumulation, population growth rate, photosynthetic potential and other indicators of conventional japonica rice decreased significantly with the reduction of planting density. The average dry matter weight of population in high density treatment at maturity stage was 11.8% and 8.9% higher than that in medium density treatment and low density treatment respectively, and without significant difference between the low density treatment and control. For the population growth indexes of hybrid rice, medium density treatment was the highest, and there was no significant difference between high density treatment and low density treatments. The actual yield in high density treatment was between that in medium and low density treatments, besides, that in high density treatment of indica hybrid rice was equal to that in low density treatment, but significantly lower than that in medium density treatment by 3.0%. Consequently, for conventional japonica rice and varieties with big panicle and numerous grain in agricultural production, the hill spacing of 12 centimeters could reach high yield, while for hybrid rice and big heavy panicle varieties, increasing the hill spacing appropriately was helpful to improve the percentage of spike-forming tillers and develop the advantage of panicle type, resalting in high yielding and high efficiency production.