With the increase of zinc treatment time, the content of H₂O₂ in each group is also increasing. The results showed that the longer zinc treatment time, the greater the stimulation to Dendrobium nobile , and the more H₂O₂ produced. On the 21st day, from the zinc concentration of 200 μmol/L, compared with CK group, the content of H₂O₂ increased significantly, but when the zinc concentration was between 400 μmol/L-1000 μmol/L, the content of H₂O₂ in each zinc treatment group increased slowly, there was no significant difference between the groups. When zinc concentration increased to 2000 μmol/L, the content of H₂O₂ increased significantly. The results showed that the zinc concentration of 2000 μmol/L and long-term treatment could make Dendrobium nobile produce more H₂O₂.