Abstract: The effect of thinning on mixed forest of Chinese fir and Manglietia yuyuanensis was studied in this paper.The result showed that thinning was beneficial to the growth of rare tree species-Manglietia yuyuanensis and remained Chinese fir.Compared to those of control,the average DBH and tree height of Manglietia yuyuanensis were improved by 47.2% and 22.1% respectively,the average DBH,tree height and standing volume of Chinese fir were significantly improved by 59.7%,32.3% and 177% respectively after six years of thinning.The average individual net output of Manglietia yuyuanensis and Chinese fir were 7.02 kg·a-1 and 2.13 kg·a-1 respectively.Thus,the stand productivity was enhanced,the output of rare was broad-leaved tree was protected and enhanced,and the stand structure was improved by thing,and then the foresty brought ecological function and social benefit into play mueh more.