Abstract: Based on the data of the height and basal diameter growth of Magnolia dawsoniana grafted seedlings,the growth rhythm was analyzed by Logistic equation.The results showed that (1) taking Magnolia biondii as the rootstocks for grafting M.Dawsoniana could obviously promote the growth of M.Dawsoniana.The annual growth of grafted seedlings was closer to the growth of the sprout seedlings of M.biondii and significantly higher than the growth of 2-year old M.Dawsoniana seedlings.(2)The growth of seedling height exhibited a "S-shaped" curve as "slow-fast-slow" while that of basal diameters growth were presented as a "double S-shaped" curve as "slow-fast-slow-fast-slow".(3) The growth period of seedling growth process could be divided into three parts:the initial growth stage (before June 26th),the fast-growing period (from June 26th to August 15th) and the late growth period (from August 15th to October 18th),The duration of fast-growing period was 50 days,and the fast-growing period of cumulative growth accounted for 56.92% of the theoretic maximum number.(4) The basal diameter growth process could be divided into three stages:the initial growth stage (before May 27th),the fast-growing period I (from May 27th to June 12th),the transition period (from June 12th to July 26th),the fast-growing period Ⅱ (from July 26th to August 13th) and the late growth period (from August 13th to October 18th),besides,the cumulative time of the fast-growing period I and the fast-growing period Ⅱ were 34 days,and the total cumulative growth accounted for 61.8% of the theoretic maximum number.