Abstract： Objective To investigate the impact of fluid resuscitation with different crystalloid-colloid ratios on hemodynamics and prognosis in pediatric patients with severe acute pancreatitis (SAP).Methods Forty-eight patients with pediatric SAP were given supportive therapy and fluid resuscitation in the early acute phase.Patients were randomly divided into low crystalloid-colloid ratio group and high crystalloid-colloid ratio group according to crystalloid-colloid ratio (3:1) as the cutoff value,with 24 patients in each group.Hemodynamic parameters were observed at the time point of before fluid resuscitation (T0),and 0 (T1),24(T2),48 (T3) hours after resuscitation,the quantity of fluid resuscitation,complications and mortality of the two groups were compared.Results Central venous pression(CVP),Cardiac index (CI),Extravascular lung water index (ELWI),Intrathoracic blood volume index (ITBI) at T1,T2,T3 were significantly higher than those at T0 in both groups (P ＜ 0.05).The ELWI of high crystalloid-colloid ratio group at T2 was significantly higher than that in low crystalloid-colloid ratio group [(14.9 ± 4.2) ml/m2 vs (11.9 ± 3.1) ml/m2,P ＜ 0.05)],but the other hemodynamic parameters of both groups were not significantly different.The 24 h total volume of infused fluid,24 h total volume of colloid,24 h total amount of fluid retention in the third space,24 h crystalloid-colloid ratio was (4931 ± 518),(3963 ± 552),(2619 ± 367) ml and 4.47 ± 0.41 in high crystalloid-colloid ratio group,the corresponding values in low crystalloid-colloid ratio group were (4436 ±547),(3348 ±421),(1711 ± 278)ml and 2.31 ± 0.37,the values in high crystalloid-colloid ratio group were significantly higher than those in low crystalloid-colloid ratio group (P ＜ 0.05).However,24 h total volume of colloid in high crystalloid-colloid ratio group was significantly lower than that in low crystalloid-colloid ratio group [(922 ± 452) ml vs (1117 ± 390) ml,P ＜ 0.05].The incidence of mechanical ventilation rate,cardiac insufficiency,MODS was 58.3％,33.3％,25.0％ in high crystalloid-colloid ratio group,which were significantly higher than those in low crystalloid-colloid ratio group (25.0％,8.24％,4.2％,P ＜ 0.05),but the mortality was not significantly different.Conclusions A low crystalloid-colloid ratio should be considered for controlled fluid resuscitation in pediatric SAP patients in order to effectively improve hemodynamics,reduce fluid retention,and improve the prognosis.