Abstract: A study on the radiation and leaf area vertical distribution in relation to the growth of 8-year-old Chinese fir plantations of 5 densities was conducted.The leaf area vertical distribution and LAI were closely related to stem density.The crown form varies from conic to cylindric with the increase of stem density.The LAI rises at first and then declines with the increase of density.The extinction of radiation sharpened when the crown density increased.The extinction leveled at the depth of 3/4 forest heights from the tops of forest canopies.Calculating the extinction coefficients by means of accumulated leaf area index separately for each crown layer can minimize the errors caused by the irregularity of leaf distribution.Four indices,i.e.,absorption of radiation,LAI,biomass of individual tree and averaged annual increment of biomass were used to have a comprehensive evaluation on the growth of Chinese fir of 5 densities.The results showed that the plantation with a stem density of 2m×1 m was the best one among the 5 young plantations.