Purple majesty (Pennisetum glaucum) named as pearl millet belongs to Poaceae, Pennisetum. Purple majesty as an important cereal crops was once grown as livestock feed in the world, but now is widely been grown as ornamental plant. Up to day, most studies are concentrated in evaluating and screening cultivars, but the research related biological characteristics is less. In the present study, purple majesty was used to study the effect of signal chemical salicylic acid on photosynthetic characteristics, chlorophyll fluorescence parameters and membrance lipid peroxidation under drought stress. Purple majesty seedlings with four to five leaves were treated with signal chemical salicylic acid and drought stress. Photosynthetic and chlorophyll fluorescence parameters were determined by LI-6400, membrance lipid peroxidation parameters were determined by chemical method and chloroplast membrane structure were observed by electron microscope. The results showed that: (1) Drought stress could destroy the chloroplast membrane structure, decrease the number of chloroplast grana, obscure the grana stacking and loose the array of grana lamella, while salicylic acid could protect chloroplast membrane structure; (2) Drought stress reduced the contents of chlorophyll b and total chlorophyll while salicylic acid increased the contents of chlorophyll a, chlorophyll b, total chlorophyll and carotene under drought stress; (3) Drought stress reduced the net photosynthesis rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs), the light saturation point (LSP) and dark respiration rate, and increased the light compensation point (LCP), the CO₂ saturation point (CSP), the CO₂ compensation point (CCP) and light respiration rate significantly, while salicylic acid increased the net photosynthesis rate (Pn), transpiration rate (Tr), the light saturation point (LSP) and dark respiration rate, and reduced the light compensation point (LCP), the CO₂ saturation point (CSP), the CO₂ compensation point (CCP) and light respiration rate significantly; (4) Drought stress reduced the photochemical efficiency of PSⅡ (F_v/F_m) and actual photochemical efficiency of PSⅡ (Φ_PSⅡ), and increased the relative conductivity of leaves and the content of malondialdehyde (MDA), while salicylic acid increased the photochemical efficiency of PSⅡ (F_v/F_m) and actual photochemical efficiency of PSⅡ (Φ_PSⅡ), and reduced the relative conductivity of leaves and the content of malondialdehyde (MDA). All the results showed that Signal chemical salicylic acid mitigates the negative effects of drought on photosynthesis and membrance lipid peroxidation of purple. The present study provides a reference for seedling preparation and field plantation of pearl millet under drought condition and for the screening of drought-tolerant and water-saving cultivars.