Abstract: The research aimed to define the growth rhythm of S. superba container seedlings and screened the key quality indicators which reflected the quality of S. superba container seedlings. Employing the peat soil, perlite and the local rice husk to be mixed into composition of matrix and also biodegradable nonwoven to be container, the variation regularities of seedlings height, ground diameter, leaf quantity and biomass of S. superba container seedlings within 195 d were studied, and the correlation analysis and differentiation of 14 indicators, including seedlings height, ground diameter, chlorophyll content, soluble sugar content, root vigor and so on of S. superba container seedlings were researched after 195 d growth. The results showed that after transplant seedlings, the height, the diameter, the amount of leaf and the biomass per plant of the seedlings presented the same growth trend within 195 d. The growth rate were slow during the first 75 d after transplant seedlings, but after 75 d, the growth of height and diameter gradually entered a fast-growing period, and the rate gradually slowed down since 165 d after transplant seedlings, entering a lignification period. The differentiation degrees of ground diameter, total fresh weight and mass index in all quality indicators were higher than that of other indicators, and significantly correlated with other indicators. These findings indicate that S. superba container seedlings grow and develop well, and mass index, fresh weight and diameter and other morphological indexs are the crucial indexes to evaluate the quality of S. superba container seedlings, and root vigor, soluble sugar content and total nitrogen content are considered as the secondary indexes, and the auxiliary indexes consist of rates of height to diameter and root/shoot.