Abstract: In this paper, eight species of Iris plants were used as experimental materials, and the pot culture was executed to control water naturally and continuously. Five drought treatments were set for 0 d（80% to 85% of field water capacity）, 7 d（70% to 75% of field water capacity）, 14 d（60% to 65% of field water capacity）, 21 d（40% to 45% of field water capacity） and 28 d（20% to 25% of field water capacity）. The comprehensive evaluation of drought resistance of Iris plants was carried out based on principal component analysis and membership function value. The results showed that the leaf length, fresh leaf weight and dry leaf weight of most Irises plants decreased to varying degrees at 28 d while the fresh leaf weight decreased significantly, compared with the control. And, the effects of soil drought on growth indexes of Iris plants were as follows leaf fresh weight＞leaf length＞leaf dry weight. The results of drought resistance of Iris plants were different with different drought resistance indexes under drought stress, and part of indexes showed significant correlation. The results of comprehensive evaluation of drought resistance showed that the drought resistance ability of Iris tectorum（No.4）, Iris germanica（No.7） and Iris japonica（No.8） were stronger. Cell membrane permeability（CMP）, peroxidase（POD） activity and superoxide dismutase（SOD） activity could be important screening indexes for drought resistance of Iris plants. The results showed that the physiological conditions of the I. tectorum, I. germanica and I. japonica with strong drought resistance were better while the soil water content was 60%-65% of the field water capacity. Therefore, the irrigation amount could be controlled at 60%-65% of the field water capacity while the three kinds of Iris plants were applied in gardens, so as to achieve the purpose of water-saving cultivation.