The tropical forests play an important role in global carbon cycling, so the investigation of the growth dynamics of tropical trees and their relationships with climate factors are important for predicting the impact of climate change on the carbon fixation capacity of tropical forests. There is still limited knowledge for the seasonal radial growth dynamics and xylogenesis of tropical tree species. In this study, we used microcoring and band dendrometer to monitor the seasonal radial growth variations and xylogenesis of a tropical deciduous tree species Melia azedarach in Xishuangbanna Tropical Botanical Garden during 2021. Combined with the monitoring of environmental factors, the relationships between radial growth rate of M. azedarach and environmental factors were also analyzed. The results showed that the enlarged cells of M. azedarach in 2021 began to appear on March 1 (Day of year (DOY): 60.2±1.6), and cell wall thickening of M. azedarach ended on December 11 (DOY: 345.4±3.1), the annual xylem growth of M. azedarach was 7.76 mm, and the maximum growth rate was 0.039 mm/d. The results of band dendrometer showed that growth of M. azedarach started on March 18 (DOY: 76.6±8.6), and ended on October 13 (DOY: 286.4±6.8), and the annual radial growth was (6.25±2.35) mm. The maximum growth rate was (0.056±0.02) mm/d. The radial growth of Melia azedarach was positively correlated with precipitation (r=0.77, P<0.001), mean temperature (r=0.61, P<0.05) and the minimum temperature (r=0.67, P<0.001), and negatively correlated with wind speed (r =-0.45, P<0.05). The study will be helpful to understand the seasonal growth pattern and growth-climate relationships for tropical tree species.