Objective To investigate the effects of acute normovolemic hemodilution(ANH)on intraoperative intracranial pressure(ICP),jugular venous oxygen saturation(SvO_2),and venous blood lactate(VBL)of patients with intracranial tumor, Methods Forty-two patients,elected to perform supratentorial intracranial tumor resection on some certain days,were randomly divided into ANH(n=21)and control (n=21)groups.Bloodletting was performed in the radial artery after anesthesia induction and the same amount of hydroxyethyl starch was injected into the internal jugular vein at the same time so as to induce the haematocrit reaching to 30% in the ANH group.ANH was not performed in the control group.Acetated Ringer's solution was used during the operation in both groups.The level of arterial partial pressure of oxygen(PaO_2),arterial oxygen saturation(SaO_2),venous oxygen partial pressure (PvO_2),mixed venous O_2 saturation(SvO_2)and VBL was measured before hemodilution(T_0),30 min after the hemodilution(T_1),1 h after the hemodilution(T_2),and at the time the operation was finished(T_3)in both groups.And the changes of ICP before hemodilution(T_0),immediate after hemodilution(T_1),30 min after the hemodilution(T_Ⅱ),and before the endocranium was cut open(T_Ⅲ)in both groups. Results The ICP value in the two groups was not significantly different at different time points;The level of SvO_2 in the control group was significantly lower than that in the ANH group at T_2 and T_3(P<0.05);Significantly decreased level of SvO_2 and increased level of VBL was found in the control group at T2 and T_3 as compared with those in the control group at T_0 and T_Ⅱ(P<0.05). Conclusion Maintaining ICP in patients with intracranial tunlor during the operation through performing ANH with Hct reaching 30%,can significantly improve the oxygen supply and consumption in the brain tissue.