Abstract: Investigations have been made on the seasonal growth pattern of seedling height, collar diameter roots of Cinnamomum platyphylium one-year-old seedlings. The results are as follows.Growth stages of the seedling height can be divided by using cluster analyses of series samples. Logistic curves have been obtained to simulate the growth process of the height. There exists a positive relationship between rates of the height growth and rates of the leaf areas increment. The nitrogen (N) concentrations in the leaves have the first important influence on the height growth, phosphorus (p) concentration is the second, the last is potassium(k) concentration. The growth rate of height is closely correlated to air temperature. The ten-day changes of collar diameter growth accord with the ten-day fluctuation of rainfall. The growth of collar diameter is positively correlated to net photo-synthetic rate (NPR) of leaves multiplied by total-leave-area. It was found that there exists an alternative growth rhythm between roots growth and above-ground growth. Length of main root has an obvious effect on the spread of lateral.