Drought is a significant abiotic stress that severely impacts seed germination and seedling growth. In this study, PEG-6000 was employed to simulate drought stress conditions, and the effects of various concentrations of PEG-6000 (0%, 5%, 10%, 15%, 20%) on the germination rate, germinating potential, relative germination rate, relative germinating potential, germination index, stress index, vitality index, drought resistance coefficient and germination coefficient of Festuca arundinacea, Ryegrass, and Lyme grass seeds were investigated. The seedling fresh weight, root fresh weight, plant height, H2O2 content, O2- content, catalase (CAT) activity, superoxide dismutase (SOD) activity, chlorophyll a content and chlorophyll b content of three species of forage grasses seedlings under different drought stress conditions were measured. In this study, correlation and principal component analysis were conducted on each index. The factor loadings and contribution rates of each comprehensive index were statistically analyzed. The principal component comprehensive evaluation value of each comprehensive index of three species of forage grasses under PEG-6000 treatment at different concentrations, and the critical threshold of drought tolerance of each index to PEG-6000 concentration were calculated. The drought resistance and drought tolerance of three species of forage grasses were comprehensively evaluated. The comprehensive analysis of drought tolerance critical values and the evaluation of drought resistance indicated that the drought resistance of the three species of forage grasses was ranked as Festuca arundinacea > Ryegrass > Lyme grass, in descending order. This research is of great significance for the identification and screening of drought-resistant grass species.