Abstract: In order to explore the relationship between the photosynthetic characteristics of different leaf ages of Cinnamomum camphora, the biomass-energy tree species in rocky desertification areas and its main environmental factors, the photosynthetic factors such as net photosynthetic rate (Pn), stomatal conductivity (Gs), transpiration rate (Tr), intercellular CO₂ concentration (Ci), and the environmental factors such as photosynthetically active radiation (PAR), atmospheric temperature (Ta), atmospheric carbon dioxide concentration (Ca) and relative humidity (RH) of Cinnamomum camphora leaves in the rocky desertification areas of Kaili City, Guizhou Province in June, August and October were measured by LI6400 portable photosynthesis tester. Then, the diurnal variation of photosynthesis and light response curves of different leaf ages were studied. The correlation analysis and path analysis were further used to explain the significance of Pn at different leaf ages and its relationship with photosynthetic factors and environmental factors. The results showed that the diurnal variation curves of Pn at different leaf ages of Cinnamomum camphora showed a single peak type. The Pn showed August > October > June. The light saturation point (LSP) of different leaf ages of Cinnamomum camphora showed that August < October < June, and the difference between August, October and June was significant. The light compensation point (LCP) of different leaf ages of Cinnamomum camphora showed that August < June < October, and the difference between October, June and August was significant. The Pn of different leaf ages of Cinnamomum camphora was mainly affected by Tr, Ci and RH, and was also affected by other photosynthetic factors and environmental factors.