Abstract： Objective To investigate the optimal strategy of fluid resuscitation in the early stage of severe acute pancreatitis (SAP). Methods 60 SAP patients who received treatment in our hospital from March, 2005 to september, 2007 were randomly divided into 4 groups (n = 15) according to the different amounts of crystal and colloid in the daily resuscitation, including crystal group, combined group Ⅰ (the ratio of crystal to colloid was 4 to 1), combined group Ⅱ (the ratio was 3 to 1) and combined group Ⅲ (the ratio was 2 to 1). The levels of hematocrit (HCT), saturation of central vein oxygen (ScvO2), gastric mucosa pH (pHi), serum lactic acid as well as the advent of negative fluid balance, the amount of fluid contained in the third space, mortality rate and the incidence of multiple organ dysfunction syndrome (MODS) in different groups were compared. Results Compared with crystal group, all the parameters were significantly improved in the 3 combined groups (P < 0.05) and the strategy in combined group Ⅲ seemed to be the most effective. HCT in this group of patients was (30.3 ± 7.1) %, ScvO2 was (81.1 ± 16.2) %, pHi was 7.8 ～ 1.5, lactic acid was (1.4 ± 0.6) mmol/L, the advent of negative fluid balance was (77.0 ± 16.8) h, the amount of fluid contained in the third space was(50.2 ± 7.8)ml, mortality rate was 6.7% and MODS incidence was 20%. Conelusions In the early stage of SAP, fluid resuscitation by a combination of crystal and colloid could effectively restore blood volume, reduce the amount of fluid contained in the third space, shorten the duration of positive fluid balance, increase tissue perfusion and oxygen supply, maintain critical organs' function and significantly improve the prognosis of SAP.