Abstract: The most suitable sowing depth and sowing manner of floating nursing seedling in nutrient water bed(FNSNWB) and the effects of FNSNWB on biological characteristics of seedlings and yield were studied by using Xinong 9 as material in this paper. The results show that the most suitable sowing depth of FNSNWB was from 1.0 to 1.5 cm, and the best sowing manner was laying horizontally which the seedling rate was above 90% and the rate of seedling with seed coat was less than 6%. Meanwhile, the seedling qualities of FNSNWB, such as fresh weight of shoot, fresh weight of root, root volume, main root length, and stem diameter were better than that of the seedlings by soil nursing seedling(SNS). Compared with SNS, the lateral roots of FNSNWB grew more, the main root developed better, and the fresh weight of roots was nearly two times as heavy as that of the SNS. FNSNWB could shorten the delaying living days and improve the percent of living plants of watermelon seedling transplanting with mixed nursing material and water. Therefore, the yield FNSNWB was increased.