The results of this study indicate that Zn²⁺ had an obvious effect on the physiology and accumulation of medicinal components of Dendrobium nobile. Low concentration Zn²⁺ (< 400 μmol/L) can promote the photosynthesis of Dendrobium nobile, increase the net photosynthetic rate and transpiration rate, increase the stomatal conductance and the content of chlorophyll A and chlorophyll B, reduce the intercellular CO₂ concentration and water use efficiency. At the same time, when the concentration of zinc was 200 μmol/L and keep it for 21 days, the stimulation from zinc on Dendrobium nobile could promote the synthesis of antioxidant enzyme SOD, so as to eliminate the free radicals produced by stress. Another finding was that low concentration Zn²⁺ (< 400 μmol/L) can increase the activity of CAT, APX and ASA. However, the maximum value of GSH appeared when the zinc concentration was 800μmol/L. When the concentration of zinc was 400 μmol/L, the content of polysaccharide reached the maximum on the 7th day, the content of polyphenols reached the maximum on the 14th day, but the content of flavonoids reached the maximum on the 21th day. In addition, when the concentration of external zinc treatment reached 800 μmol/L, the content of zinc-polysaccharide in the stem of Dendrobium nobile reached the maximum on the 7th days, which indicated that a certain amount of external zinc could promote the synthesis of zinc polysaccharide and promote the transformation of inorganic zinc into organic zinc in Dendrobium nobile. This experiment also found that Dendrobium nobile can transform inorganic zinc into organic zinc, which is stored in the body in the form of zinc-polysaccharide, which greatly improves the medicinal value of Dendrobium nobile, and provides the theoretical basis for research and development of drugs and functional food of Dendrobium nobile. Meanwhile, the polysaccharide can combine with zinc well to form polysaccharide zinc chelate, which makes zinc ion lose its activity, and the polysaccharide-zinc chelate is transported to the vacuole under the action of ATP, so as to reduce the damage to Dendrobium nobile and protect it.