In the study, the effect of two different planting density (3000 trees/ha and 4500 trees/ha) on the initial growth of Cryptomeria japonica in Xitou district of the Experimental Forest, in the National Taiwan University were investigated. Results show that the early survival rate and tree height of C. japonica in two different planting densities did not influence. However, it showed that low planting density (3000 trees/ha) with the increase of the diameter at breast height on initial growth of C. japonica.