Abstract: The effects of flooding and drainage treatments on the physiological characteristics of four perennial flowers of Compositae were studied, which revealed their response to flooding stress and differences in resistance, and provided theoretical experimental references for future landscaping. The double-pot method was used to treat them with flooding stress, and physiological and biochemical indicators such as the relative water content（RWC）, free proline（Pro）, soluble protein（SP）, soluble sugar（SS）, malondialdehyde （MDA） and chlorophyll （Chl） of four perennial flowers of Compositae family were measured, comprehensively evaluated and analyzed. The results showed that, under flooding stress, RWC and SS contents of four flowers increased first and then decreased; Pro and MDA contents increased continuously; SP contents of Gaillardia aristata and Chrysanthemum morifolium increased first, then decreased and then increased, and those of Dendranthema indicum and Achillea millefolium rose first and then fell; Chl content was a trend of decreased firstly, then increased and then decreased. The four kinds of flowers maintain cell stability by increasing the content of osmotic adjustment substances, which coordinate with each other to improve their anti-waterlogging ability, thereby reducing the damage of water stress. After the waterlogging was drained, the physiological states of four flowers all recovered. The four perennial root flowers had certain differences in resisting waterlogging stress. Through the analysis and evaluation of the membership function method, it was found that the strength of the resistance to waterlogging was in the order of Chrysanthemum morifolium > Achillea millefolium > Dendranthema indicum > Gaillardia aristata. Principal component analysis was used to rank the importance of waterlogging resistance indexes, from large to small： Pro, MDA, SS, Chl, SP, RWC.

Key words: perennial flowers, flooding stress, drainage, physiological characteristics, membership function