Using 3.5 a saplings of Phoebe zhennan as experimental materials, the response of photosynthetic physiology and chlorophyll fluorescence parameters of P. zhennan under different concentrations of cadmium (Cd) stress was investigated by pot experiment.A total of 6 Cd (CdCl₂) treatment levels (0, 10, 20, 30, 40, 50 mg/kg) were set up, and the application amount of each treatment was divide into 5 equal parts and each part was applied once every two months., the photosynthesis and photosynthetic physiological indicators were measured as soon as the experiment was over. (1) With the aggravation. of Cd stress, the total amount of chlorophyll a (Chl a), chlorophyll b (Chl b), carotenoid (Car) decreased, and Chla/b gradually increased. (2) The net photosynthetic rate (P_n), stomatal conductance (Gs), and transpiration rate (Tr) decreased significantly with the aggravation of stress, while the intercellular carbon dioxide concentration (Ci) increased. (3) With the enhancement of cadmium stress, the light saturation point (LSP) and the dark respiration rate (Rd) all showed a downward trend, and the light compensation point (LCP) gradually increased. (4) Initial fluorescence (F0), maximum fluorescence (Fm), actual photon efficiency (ΦPSII), electron transfer rate The ETR and photochemical quenching coefficient (qP) decreased with the increase of cadmium stress, and the non-photochemical quenching coefficient (qN) increased gradually. As for the maximum photochemical efficiency (Fv/Fm) and PSII potential activity (Fv/F0), there was no significant change at T1-T4, and it was significantly increased at T5. (5) The dissipation of residual light energy of seedlings was mainly based on the pathway of heat dissipation, but with the increment of cadmium concentration(T3-T5), the dissipation of non-chemical reaction energy (E_x) increased, and the heat dissipation energy (D) and photochemical reaction energy (P) decreased. The photosynthesis of P. zhennan saplings were severely inhibited under low concentration of Cd(T1-T2) stress. With the further increase of Ca concentration (T3-T4), the chlorophyll fluorescence parameters changed significantly. The distribution of light energy has changed significantly, indicating that the cadmium tolerance of P. zhennan saplings is weak, so it is necessary to pay attention to the site selection for young plantation of P. zhennan,and in particular, to avoid to plant it in place where cadmium pollution is serious.