Abstract: Two-year-old Magnolia officinalis seedlings were used in this experimentation. Effects of Cd stress on the biomass, chlorophyll SPAD value, and chlorophyll fluorescence characteristics, as well as Cd contents in various parts of the plant, under 5 gradients of Cd stress including 0 (CK), 50, 100, 200, and 300 mg·kg^-1 were studied to unveil the underlying mechanism. In the seedling plants and parts, it was found that the highest accumulated Cd concentrations (dry weight) were 325.76 mg·kg^-1 in the roots, and 13.56 mg·kg^-1 in the aboveground parts. In general, 95.71%-96.23% of the total Cd accumulated on the plant were found in the roots. The seedling height decreased with increasing Cd concentration. Compared with CK, all treatment groups except 50 mg·kg^-1, showed significant decreases on SPAD chlorophyll. When the Cd concentration was low, the plants appeared to adapt and continue to grow and metabolize. Nonetheless, the PSII maximum quantum yield (Fv/Fm), actual photochemical quantum yield (ΦPSⅡ), chemical quenching (qP), and electron transport efficiency (ETR) were significantly decreased due to high Cd stress as compared to CK indicating that the energy capture from the sunlight, ETR, PSII activity, and metabolism were all suppressed resulting in damage to the plant.