Objective To investigate the predictive value of P (v-a) CO2/C (a-v) O2 in long-term clinical outcome in patients with sepsis. Methods From Jan, 2013 to Dec, 2015, a series of patients with sepsis admitted to our hospital were enrolled in this prospective study. The levels of P (v-a) CO2/C (a-v) O2, C (a-v) O2, P (v-a) CO2, lactate, ScvO2, cardiac output and APACHE Ⅱ score on admission were recorded. The predictive values of P (v-a) CO2/C (a-v) O2, C (a-v) O2, P (v-a) CO2, lactate, ScvO2, cardiac output and APACHE Ⅱ score on admission in long-term clinical outcome in patients with sepsis were compared. Moreover, the levels of P (v-a) CO2/C (a-v) O2 and cardiac output at 0 h, 6 h, 24 h and 48 h were recorded as well and their corrections were analyzed. Results When compared to the survival group, patients in the non-survival group got a significantly higher level of P (v-a) CO2/C (a-v) O2 (1.642 ± 0.233) vs (1.183 ± 0.186) mmHg/ml, (P = 0.000); a significantly lower level of C (a-v) O2 (2.827 ± 1.215) vs (3.349 ± 1.074) ml, (P = 0.035); a significantly higher level of P (v-a) CO2 (4.625 ± 0.870) vs (3.945 ± 0.781) mmHg, (P = 0.000); a significantly higher level of lactate (3.452 ± 2.216) vs (2.218 ± 2.344) mmol/L, (P = 0.024); a significantly lower level of ScvO2 (62.324 ± 12.226) vs (67.517 ± 10.885) %, (P = 0.045); a significantly lower level of cardiac output (2.571 ±1.214) vs (3.569 ± 1.345) L/min, (P = 0.000); a significantly higher level of APACHE Ⅱ score (25.329 ± 4.234) vs (18.763 ± 10.565), (P =0.000). The areas of receiver operating characteristic curve of the predictive values of P (v-a) CO2/C (a-v) O2 and cardiac output in mortality of sepsis were 0.925 and 0.920, and the best cut off values were 1.412 mmHg/ml and 3.214 L/min. Z test showed that the areas of receiver operating characteristic curve of the predictive values of P (v-a) CO2/C (a-v) O2 and cardiac output in mortality of sepsis were higher than C (a-v) O2, P (v-a) CO2, lactate, ScvO2 and APACHE Ⅱ score on admission (P < 0.05). Pearson Test showed that P (v-a) CO2/C (a-v) O2 and cardiac output were significantly corrected, the r values were -0.854, -0.901, -0.823 and -0.82, and the P values all were 0.000. Conclusions P (v-a) CO2/C (a-v) O2  is a better quota in the predicting mortality in sepsis.