Abstract: In order to promote the variety, a comparative study of drought tolerance of three Crape myrtle varieties was carried out the fuzzy mathematics subjection function method was used to evaluate the drought resistance of three varieties from the six physiological and biochemical indexes, which are prolino, soluble protein, soluble sugar, malondialdohydo, chlorophyll and glutathiono. Combining with the result of observation leaves,drought tolerance of ＇Shao Nv Hua Yu＇ is slightly stronger than ＇Northern Rose Bengal＇ and far stronger than ＇rod rocket＇. In northern of Jiangsu,promotion of the variety needs only normal moisture management.