Stipa purpurea is widely distributed on the Tibetan Plateau, and has high drought resistance. Plasma membrane intrinsic proteins are a type of aquaporin. They regulate the movement of water and are associated with plant protective reactions to biotic and abiotic stresses. We characterized a plasma membrane intrinsic protein from S. purpurea (SpPIP1) and elucidated its role in molecular aspects of the plant's response to drought stress. The full-length open reading frame of SpPIP1 was 870 bp and encoded 289 amino acids. The transcript level of SpPIP1 was higher in the root of S. purpurea than in the flower, leaf and stem. The level of SpPIP1 transcript increased significantly when treated with drought treatment. Subcellular localization result showed that SpPIP1 was localized in the plasma membrane. Ectopic expression of SpPIP1 in Arabidopsis thaliana resulted in plants with higher tolerance to drought treatment. SpPIP1 of S. purpurea may mediate plant response to arid environments.