Abstract: By using microwave extraction, the single factor and L 9 (34) orthogonal test (solvent ratio, time, temperature, power of microwave extraction) was used to to optimize the extraction process of pigment from Lagerstroemia indica flowers.The stability of the pigments from flower Lagerstroemia indica was evaluated in the presence of common oxidant, reductant, food additives and metal ions and the antioxidant activity was also studied.The results showed that the best extraction conditions was as follows:50% ethanol, temperature of 65℃, time for 5min, power for 100W, under this conditions the extraction yield (A 588) could be up to 0.805, and the pigment from Lagerstroemia indica flowers showed good stability and antioxidant activity.