Abstract： Objective To evaluate the physiological variables,which precisely and reliably reflected the effect of emergency fluid therapy for severely traumatized patients, in order to set up the ultimate criteria of optimal goal in fluid resuscitation. Method A total of 149 patients with severe trauma were given fluid resuscitation and were stratified into 3 groups with different severities of trauma as per ISS (injury severity score) and APACHE Ⅱ . Of all patients, heart rate (HR), systolic blood pressure (SBP), oxygen saturation of arterial blood (SaO2), blood gas analysis, arterial blood lactate (ABL), oxygen saturation of central venous blood (SCVO2) or oxygen saturation of mixed venous blood (SVC2), urine output, base excess (BE) and oxygenation index (OI = PaO2/FiO2) were measured and calculated. These variables were compared between groups to find out the significant differences and the relationship to response time to fluid therapy as well as complications and outcomes. Results Within 24 hours of fluid resuscitation, 127 patients reached the therapeutic goal in respect of systemic hemodynamics improved including the variables of SBP, HR and urine output, and the optimal goal of fluid therapy in 112 patients was estimated with cellular oxygen available found in the levels of ABL, BE and OI measured. These two sets of criteria (clinical signs vs laboratory findings) for determining the therapeutic goal showed significant difference in length of time taken for reaching the goal of treatment ( P < 0.05). There were significant differences in APACHE Ⅱ scores between those reaching the therapeutic goal within 24 hours and those taking longer time over 24 hours reaching the therapeutic goal or the death (P < 0.01). The duration of persistence in abnormal systemic hemody-namics and laboratory findings was longer in patients with complications or injured to death than that in survivors (P <0.05 -0.01). Conclusions In addition to the stability of vital signs, tissue perfusion and cellular oxy-genation should be taken as ultimate criteria of successful fluid resuscitation for severely traumatized patients judged by means of measuring the ABL, BE and OI variables.