Abstract: Taking the droughtsensitive Dactylis glomerata line “01998” and droughttolerant cultivar “Baoxing” as test materials, a pot experiment was conducted to study the effects of drought stress on the seedlings root growth, physiological characteristics, and leaf photosynthesis, aimed to approach the differences in the droughttolerance mechanism of different D. glomerata lines (cultivars). Under drought stress, the root vitality and root number of “01998” and “Baoxing” presented a trend of increased first and decreased then. When the soil relative moisture content decreased to 30%, the root vitality and root number of “01998” and “Baoxing” increased significantly and reached the maximum. Drought stress decreased the relative water content, leaf chlorophyll content, net photosynthesis, transpiration, and stomatal conductance, but increased the electric conductivity and intercellular CO₂ concentration of “01998” and “Baoxing”. Under drought stress, the leaf area per plant of both “01998” and “Baoxing” decreased, and the underground and aboveground plant biomass of “01998” decreased while that of “Baoxing” had less change.