Objective To investigate the clinical effects and the management of combined using of zerobalanced ultrafiltration(ZBUF) and modified ultrafiltration(MUF) in severe infant open heart surgery with cardiopulmonary bypass(CPB) , in order to evaluate the feasibility and clinical significance of combination of ZBUF and MUF. Methods 20 pediatric patients diagnosed as complicated congenital heart disease had been involved, which included 12 males and 8 females with 12.6±7.5months of age and 8.5±3.3 kg of weight. Gambro FH22 hemofilter was selected in all patients. The typical MUF method was chosen. ZBUF was done during CPB and MUF was performed after CPB. The variety of hemodynamics, blood gas, concentration of electrolytes, inflammatory media and change of the plasma colloid osmotic pressure(COP) were measured at several time points. Filtrate was salvaged to detect the level of tumor necrosis factor alpha (TNF-α) and interleukine-8 (IL-8). Results Mean arterial pressure(MAP) was significantly higher(P=0.001) after MUF finished in all patients. Lactate acid (LAC), TNF-α and IL-8 had no significant difference before and after ZBUF. COP was significantly higher after MUF than that after ZBUF(P=0.002). Concentration of TNF-α in MUF filtrate was significantly higher than that in ZBUF(p=0.036). Conclusion Combined using of ZBUF and MUF has the effective ability of removing the inflammatory mediators and ameliorating system immunoreaction in pediatric CPB. MUF can improve the respiratory and heart function through decreasing the body water and increasing COP and hematocrit.