Abstract: In order to determine the factors affacting seedling quality of mechanical transplanting rice, Zhendao6217 was used to investigate the effects of different sowing densities, irrigation management and strong dry rice promoter on rice seedling quality. The results showed that as the sowing density was lower, seedling quality was superior, but the circuvoluting roots were too worse to curl up for mechanical transplanting. When the sowing density was higher, rice seedling quality became bad, which made it difficult for rice seedling to regreen and revive. The suitable sowing density was around 739～924 g/m². Dry rice seedling was more beneficial to grow vigorous rice seedlings, and had more advantages to prolong the seedling age. The application of moderate amount less than 1% of strong dry rice promoter could take the same effect as fertilizing.