An ultrasonic enhanced salt-containing hydrodistillation (UESHD) method for separating essential oil from lavender (Lavandula angustifolia) flowers was investigated using response surface methodology (RSM). The experimental data obtained from a 27-run experiment were fitted to a second-order polynomial equation. The optimal conditions were determined by the 3D response surface and the contour plots derived from the models. The efficiency of UESHD and conventional hydrodistillation (HD) was compared. The extraction yield of UESHD was two-fold higher than that of HD. In addition, GC-MS results indicated some differences in composition and content between the two essential oils from UESHD and HD.