Abstract: To investigate the effects of organic selenium on the growth of Dendrobium officinale and D. nobile in tissue culture seedling, this study examined the impact of spraying different concentrations of organic selenium fertilizer on weight, Se content, as well as chlorophyll, polysaccharide, and flavonoid contents in the seedlings. The results showed that all measured indices in both Dendrobium species increased with elevating concentrations of organic selenium. For D. officinale seedlings, the weight, Se content, chlorophyll, polysaccharide, and flavonoid levels showed significant increases when the organic selenium concentration ranged from 1.00 to 1.50 mg/L. At the concentration of 1.50 mg/L, all parameters reached their peak levels. For D. nobile seedlings, the content of all indices significantly increased at organic selenium concentrations between 0.75 and 1.25 mg/L, and peaked at a concentration of 1.25 mg/L. This finding demonstrated that appropriate organic selenium effectively promotes the growth of both D. officinale and D. nobile in tissue culture seedlings.