To better understand growth characteristics of heartwood and sapwood and variation in heartwood formation of Catalpa bungei,a series of experiments were conducted to measure ring number,and widths of heartwood and sapwood at different tree heights by using tree-ring measuring station.A regression model of relationship between heartwood and tree growth was established.The results showed that annual ring widths of the trees reached peak at the 10th～15th year and could maintain the peak in 10 years.The heartwood started to form at age 5.26 a,and the heartwood growth rate was 0.90 rounds/a.It was concluded that Catalpa bungei is a hardwood species with a short growing and harvesting period,an early heartwood forming period and a fast growing rate.