Landscape plant Hylotelephium spectabile is a species of flowering plant in the stonecrop family Crassulaceae, which is native to China and Korea. The plant was used as an experimental material to investigate photosynthetic characteristics and antioxidant enzyme activity after treatment with different zinc sulfate concentrations. When the seedlings of H. spectabile were 15 cm high, they were transplanted to plastic pots (20 cm in diameter and 25 cm in height) filled with sand and watered daily. The culture condition was (26±4)℃, photoperiod 16 h light/8 h darkness, RH 50%-60%, and PPFD 500 mmol/m² S. After 7 days of culture, the seedlings were divided into seven groups for different treatments, including control group, 40, 80, 160, 320, 800, and 1600 mg/kg zinc stress treatment. ZnSO₄ was dissolved in DD water, and plants were watered weekly. After 35 days of ZnSO₄ treatment, three plants per treatment were collected for analysis. Relative plasma membrane permeability, MDA, SOD, POD, CAT, and chlorophyll content were measured in the present study. MDA is a final decomposition product of lipid peroxidation induced by oxidative stress and has been used as an indicator of lipid peroxidation. MDA content was determined by thiobarbituric acid (TBA) reaction to determine superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), and peroxidase (POD, EC 1.11.1.7) activities, and 0.3 g of fresh leaf tissue was ground to a fine powder in liquid nitrogen and homogenized in 2 mL and 59 mM phosphate buffer (pH 7.8) containing 0.1 mM ethylenediaminetetraacetic acid (EDTA) and 4% polyvinypolypyrrolidone (PVPP). After centrifugation at 15000 g, 4℃ for 20 min, the supernatants were used for enzyme activity assays. SOD activity was determined by inhibiting the photochemical reduction of nitroblue tetrazolium (NBT) at 560 nm. The amount of enzyme needed to inhibit 50% of NBT photoreduction was defined as one unit of SOD activity. The CAT and POD activities were monitored by measuring H₂O₂ consumption at 240 nm and guaiacol oxidation at 470 mm respectively. The CAT and POD activities were calculated as described previously. Three biological replicates of each treatment were independently performed. The net photosynthetic rate (P_N), stomatal conductance (G_S), transpiration rate (E), and intercellular CO₂ concentration (Ci) of leaves were determined at 09:00 AM using a portable open flow gas exchange photosynthesis system LI-6400. The measurements were repeated six times for each blade from the same position of five plants in each treatment group, and the averages were recorded. The results show that relative plasma membrane permeability, MDA content, and POD and CAT activities increased with increasing ZnSO₄ concentration. However, thenet photosynthetic rate, intercellular CO₂ concentration, stomatal conductance, and transpiration rate decreased with increasing ZnSO₄ concentration. The chlorophyll content was decreased after a slight ZnSO₄ treatment and increased higher than the control after a high concentration ZnSO₄ treatment. The SOD activity did not vary significantly under zinc stress. This finding suggests that increased antioxidant enzyme activity and closed stoma to reduce water loss may be the main reasons for reducing the toxic effect of Zn, which may be explained by the strong ability of H. spectabile to resist Zn stress.