Objective To evaluate the effects of different doses of ephedrine combined with hydroxyethyl starch as a volume preload for preventing hypotension in caesarean section before combined spinal and epidural anesthesia.Methods 250 pregnant wemen undergoing cesarean section were randomly allocated into the control group (n =50) and the observation group(n =200)(group was divided into A,B,C,D group,each group 50 cases).Control group preloaded Lactated Ringer's solution 250ml before CSEA.A group preloaded hydroxyethyl starch combined with 5mg ephedrine; B group preloaded hydroxyethyl starch combined with 10mg ephedrine.C group preloaded hydroxyethyl starch combined with 15mg ephedrine; D group preloaded hydroxyethyl starch combined with 15mg ephedrine.The parturient SBP,HR and untoward reaction were monitored in five experimental groups.Results Compared with T0 A group parturient SBP was lower at T1,T2,T5 [(111.8 ± 17.18)mm Hg,(114.58 ± 19.80)mm Hg,(115.06 ± 10.39) mum Hg vs (120.88 ± 13.24) mm Hg,all P ＜ 0.05)].Compared with B,C,D group,statistical differences were found at T1,T4,T6[(111.8 ± 17.18)mm Hg vs (120.78 ± 14.47)mm Hg,(118.56 ± 14.25)mm Hg,(118.42 ± 18.71)mm Hg.(125.58 ± 14.45) mm Hg vs (120.02 ±21.15)mm Hg,(115.92 ± 17.56)mm Hg,(119.00 ±12.49)mm Hg.(118.08 ±9.09)mm Hg vs (121.52 ± 10.92) mm Hg,(116.04 ± 11.61)mm Hg,(124.98 ± 9.16) mm Hg,all P ＜ 0.05].Compared with T0 parturient HR was undulation at T1,T5 (P ＜ 0.05).Compared with C,D group,statistical differences were found at T1,T3,T4,T6 [(82.92 ± 19.55) times/min vs (98.86 ±17.82)times/min,(96.72 ± 17.91) times/min.(89.04 ± 16.68) times/min vs (92.10 ± 16.55) times/min,(98.46 ± 19.49) times/min.(87.56 ± 17.13) times/min vs (98.86 ± 16.76) times/min,(88.58 ± 19.22) times/min.(93.20 ± 14.07) times/min vs (98.80 ± 11.69) times/min,(90.98 ± 10.93) times/min.all P ＜ 0.05].In B and C group,parturient SBP and HR were steady and the untoward reaction was very few.Although parturient SBP of D group was steady,but HR obviously fast during operation (P ＜ 0.05).Compared with B,C group,statistical differences were found at T4,T6 (P ＜ 0.01).Conclusion The optimum dose is 10 ～ 15 mg of ephedrine.It combined with hydroxyethyl starch as a volume preload can keep the stable of blood circulation.