Abstract: Studies were made of the growth characteristics of Idesia polycarpa planted in Ningqiang County of Shanxi province by the stem analysis method. The results showed that the DBH growth of Idesia polycarpa was earlier than the tree height growth. The current annual increment and mean annual increment of DBH almost reached maximum at around 15 years at the same time,while the tree height was later about 5 years. The DBH of fast-growing period was about 10 years to 17 years. The DBH growth entered the overmature period at about 19 years,while the tree height growth was at 22 years,later than DBH growth. The current annual increment of timber volume reached maximum value about 0.009086 m³ at 20 years while the mean annual increment did not yet reach the maximum value. The current annual increment and mean annual increment of timber volume were not intersected before 39 years,namely,without reaching the quantitative maturity. Consequently,its rational rotation was after 39 years. The tree stem of Idesia polycarpa was basically stable at 25 years,and the breast height form factor was about 0.4.