Abstract: Investigation was carried out on the undergrowth vegetation of Larix principis-rupprechtii plantation with the different thinning intensities in order to understand the effects of tending and thinning. Results indicated that species richness, mean height, mean density, species diversity indices decreased gradually with the increase of retention density. The undergrowth vegetation with 600 plants/hm² and 900 plants/hm² had the similar indices values but differed considerably with others. Species composition was similar greatly among the lower densities but more different among the lower and higher ones. That Larix principis-rupprechtii plantation, 40-year-old and 10 meters'height with 1500 plants/hm² was retained to the density of 900 plants/hm²,which was more reasonable.

Key words: Larix principis-rupprechtiiMayr, intermediate cutting, reserve density