Abstract: The drought resistance of 15 germplasms of Iris lactea var chinensis from different populations in northern China at the seedling stage was comprehensively identified and evaluated in a green house using the simulated drought stress and rewatering method. The relative electrical conductivity rate (REC), content of malondialdehyde(MDA), free proline accumulation (Pro), relative water content of leaves (RWC), SPAD value of chlorophyll, and relative growth rates (RGR) were measured at 0, 5, 10, 15, 20 and 25 d of drought stress and at 5 d after rewatering. Three drought resistant classes (high drought resistance (HDR), medium drought resistance (MDR), and weak drought resistance (WDR)) were classified using the maximum distance cluster method, and the variation trends and rules of physiological indexes were analyzed. The REC, Pro, and MDA of three different drought resistant classes showed a gradual increasing trend in the order HDR<MDR<WDR. The REC showed no significant difference between the three drought resistant classes before stress day 20, but there was a significant (P<0.05) difference at 25 d. There was no significant difference in Pro or MDA between the three drought resistant classes before stress day 15, but there was a significant (P<0.05) difference at days 20 and 25. The SPAD value of chlorophyll and RWC showed gradual decreasing trends in the order HDR<MDR<WDR. The SPAD value and RWC had significant differences at days 20 and 25 between the three drought resistant classes. The physiological indexes recovered to different degrees after rewatering.