Abstract: In order to find a new method to improve the ornamental value and economic value of Dendrobium denneanum, Dendrobium denneanum was used as the experimental material to study the effect of light quality on its morphological and physiological indexes. Red and blue light was used in the experiment. The treatment groups were T1 group (red: blue = 3∶1), T2 group (red: blue = 1∶1), T3 group (red: blue = 1∶3), and the control group was white light. All the treatments were irradiated for 2 hours every day, and samples were taken for detection at 7, 14, 21 and 28 days. The results showed out: (1) T1 light quality (red light: blue light = 3∶1) could effectively increase the stem length of Dendrobium denneanum after 7 days of irradiation, and could promote the stem diameter after 21 days of irradiation; (2) T2 light quality (red light: blue light = 1∶1) could promote the stem length after 7 days of irradiation; (3) T3 light quality (red light: blue light = 1∶3) could effectively prolong the flowering period of Dendrobium denneanum, and could effectively increase the content of chlorophyll a and b at day 7th, while could effectively increase the content of soluble protein at day 21. The results indicated that different ratios of red and blue light irradiation could effectively regulate the flowering period and growth of Dendrobium denneanum and increase its ornamental value.