Abstract: To provide reference for the seedlings, planting and application of Pennisetum glaucum ‘Purple Majesty’ in Chongqing, for screening and research of other turf grass vegetation, and contribute to enrich the Chongqing garden ground resources, Pennisetum glaucum ‘Purple Majesty’ was used as the material, and the author set high temperature stress and low temperature stress to study roots activity and root morphology indicators of purple pearl millet seedlings under temperature stress. The results indicated that: (1) high and low temperature stress made root activity decrease rapidly, salicylic acid treatment significantly improved the seedlings root activity at 3rd and 5th day under high temperature stress, 5th and 7th day at the stress of low temperature. (2) High and low temperature stress inhibited the root system growth of Pennisetum glaucum ‘Purple Majesty’ seedlings roots, the total root length, root surface area and root volume reduced, the impacts of low temperature stress on the total root length were greater than high temperature stress. Salicylic acid treatment significantly increased the surface area of the root under high temperature stress.