Thinning is an important activity employed in forest management. To date, studies have mainly focused on the effects of thinning on the growth of trees during the same thinning period. In this study, plantation Pinus massoniana Lamb. near maturity were thinned at varying intensities and an economically important species, Cinnamomum cassia Presl., was planted beneath the thinned canopy. The aim of the study was to explore the effects of the extent of thinning on the essential oil content and its components of C. cassia in different parts of the plant, as well as the economic feasibility of the P. massoniana–C.cassia management model. Thinning significantly reduced the oil yield in the bark and branches of C. cassia, but hardly impacted the oil yield from C. cassia leaves compared with pure C. cassia forest(CK). Among the different thinning treatments, both light(T.4) and extensive(T.1)thinning reduced the oil yield of C. cassia bark and new branches. The concentrations of the main aldehydes differed in different parts of the plant and were affected by the extent of thinning. The influence on cinnamaldehyde in the bark was minor, but was much greater in the branches and leaves. Both the oil yield and content of cinnamaldehyde showed that moderate(T.3) thinning was more favorable than other thinning models. These results not only provide a potentially promising model for the transformation of low–yield artificial pure forests of P. massoniana in the future, but also offer a reference for the management of artificial mixed stands. To date, studies have mainly focused on the effects of thinning on the growth of trees during the same thinning period. In this study, plantation Pinus massoniana Lamb. Near maturity were thinned at varying intensities and an economically important species, Cinnamomum cassia Presl., was planted beneath the thinned canopy. The aim of the study was to explore the effects of the extent of thinning on the essential oil content and its components of C. cassia in different parts of the plant , as well as the economic feasibility of the P. massoniana-C.cassia management model. Thinning significantly reduced the oil yield in the bark and branches of C. cassia, but hardly impacted the oil yield from C. cassia leaves compared with pure C Among these different thinning treatments, both light (T.4) and extensive (T.1) thinning reduced the oil yield of C. cassia bark and new branches. The concentrations of the main ald The influence on cinnamaldehyde in the bark was minor, but was much greater in the branches and leaves. Both the oil yield and content of cinnamaldehyde showed that moderate (T .3) thinning was more favorable than other thinning models. These results not only provide a potentially promising model for the transformation of low-yield artificial pure forests of P. massoniana in the future, but also offer a reference for the management of artificial mixed stands.