Objective To observe the change and relation between heart rate variability (HRV) and renin-angiotensin-aldostemne system (RAAS) under epidural anesthesia.Methods 16 cases patients ASAⅠ-Ⅱwere chose for epidural anesthesia.HRV,MAP and RT had been monitoring at pre-anesthesia (T1),15 min after inducing (T2),1 min after incising (T3),1 min pre-probing (T4),5 min after dragging uterus (T5), 1min after cutting uterus (T6) and the end point (T7).At same time,renin angiotensin and aldostemne were measured by drawing radial arterial blood when it was T1,T2,T3,T5,T7.Results Comparing with T1,LF/ HF increased significantly (P