Objective：To observe the relationship between pathologic oxygen supply dependency and energy metabolism in organ tissues, and to explore the significance of this dependency as to evaluate tissue oxygenation. Methods: The model of septic shock was established by cecum ligation and puncture(CLP). SD rats were randomized to 7 groups: pre-CLP, 2, 4, 5, 6, 7 and 8h after CLP. The parameters of oxygen kinetics were measured just before rats were killed. Liver, heart and kidney tissues were removed quickly and tissue phosphocreatine (PC) and adenosine triphosphate (ATP) were assayed using the luciferase enzyme system. Results： Biphasic relationship between systemic oxygen delivery (DO2) and oxygen consumption (VO2) was exhibited. DO2 decreased progressively and lowered to a value of critical DO2 (cDO2) at 6 h after CLP. Pathologic supply dependency of VO2 on DO2 existed below cDO2. At 5 h after CLP, PC levels were lowered (P＜0.05) in liver tissues. Reductions both in hepatic ATP and renal PC and ATP levels were present. Myocardial PC and ATP levels decreased significantly (P＜0.01) at 6 and 7 h after CLP, respectively. Conclusion： The existence of pathologic dependency of VO2 on DO2 was indicative of the defect of energey metabolism. That abnormalities in renal and hepatic tissues began to exist before cDO2 appeared. Further management to prevent cellular bioenergetic failure should be taken in early septic shock.