Herbaceous peony is a kind of perennial flowers with a strong adaptability and a good application prospect especially in arid region. ‘Da Fu Gui’, ‘Fen Yu Nu’, ‘Karl Rosenfield’, and ‘Duchesse de Nemours’ were used to study the effects of different soil water content on phenotypic traits, water physiological index and other physiological indexes, and drought resistance of four cultivars by pot experiment. Principal component analysis and subordinate functions were used to evaluate the drought resistance. The four cultivars could be ranked, in decreasing levels of drought resistance, as: ‘Karl Rosenfield’, ‘Duchesse de Nemours’,‘Fen Yu Nu’, and ‘Da Fu Gui’. This will provide a scientific basis for the application and cultivation of herbaceous peony in arid regions.