Abstract: In this study, 20 Hemerocallis lines were used as test materials to measure the indexes of leaf wilting grade, leaf relative water content, leaf water loss rate, and relative electrical conductivity under field natural drought stress.And, the drought resistance of 20 Hemerocallis lines was comprehensively evaluated by membership function, and the cluster analysis method was also used to analyze the 20 Hemerocallis lines.The results showed that, with the aggravation of natural drought stress, leaf wilting grade of Hemerocallis of 20 lines showed an increasing trend, and the variety Taigu 1 was the most obvious.The relative water content of leaves decreased gradually, and the decreasing amplitude of Hemerocallis variety Jiaocheng 3 was the least.The water loss rate of leaf increased gradually, and the water loss rate of America 72 reached the maximum when the soil reached severe drought.The relative electrical conductivity of blades increased gradually.The drought tolerance of Hemerocallis lines could be sorted from strong to weak based on subordinative function value followed as Zuoquan 1,Qinshui 1,MG 1,Wutaishan 1,Taigu 1,Moluogezhixia, MG 72,Jinwawa, Huangxiuke, Guanghuixianlu, MG 35,licheng 4,Jiaocheng 3,MG 24,Xiangbao, Zezhou 2,Yangcheng 1,Lishan 1,Xintiehong and MG 18.The 20 Hemerocallis lines could be divided into three groups by comprehensive evaluation and cluster analysis of the results.The Zuoquan 1,Qinshui 1 and MG 1 were the most drought-tolerant lines, while Jiaocheng 3,Zezhou 2 and Licheng 4 were relatively drought-tolerant lines, and the other 14 varieties were non drought-tolerant lines.