Abstract: To improve the scientific basis for managing Chamaecyparis hodginsii plantations,this study analyzed the growth response of 50-year-old C. hodginsii in mixed-species planting. The results showed that:①Mixed-species planting altered the resource allocation strategy of C. hodginsii,leading to homogenized height growth,with the mean value being 6. 22% lower than that in the monoculture,alongside reduced dispersion. In contrast,both the diameter at breast height(DBH) and individual tree volume exhibited growth differentiation,with their coefficients of variation and dispersion significantly increased. ②Mixed planting broadened the diameter class distribution of C. hodginsii from 5 in the monoculture to 7 classes. It facilitated the production of high-value large-diameter timber in the highest class(Class Ⅷ),with a mean individual tree volume of 0. 8294 m³(70. 20% higher than that in the monoculture),while also significantly increasing the proportion of small-diameter timber(30. 23%),indicating notable structural differentiation. ③Although the stand volume of C. hodginsii alone in the mixed plantation was 21. 95% lower than that in the monoculture,the inclusion of companion species(Schima superba and Cunninghamia lanceolata),increased the total stand volume by 12. 50% to 297. 37 m³·hm^-2. In conclusion,50-year-old C. hodginsii mixed plantation optimized stand structure through interspecific competition,promoting large-diameter timber formation and resource utilization,thereby effectively enhancing forest productivity.