Objective To evaluate procalcitonin (PCT) and D-dimer(D-D)combined sequential organ failure assessment(SOFA)in the diagnosis and prognosis of the elderly patients with sepsis. Methods A retrospective study was conducted of the clinical data of 117 elderly patients (age≥60 years old) who were hospitalized in Shanghai Fifth Rehabilitation Hospital from January 2016 to January 2020. PCT, D-D, SOFA scores and 28-day prognosis of the patients were recorded. According to the severity of disease, the patients were divided into septic shock group (n=32) and sepsis group (n=85). According to 28-day prognosis, the patients were divided into death group (n=35) and survival group (n=82). The two groups were compared for the indicators. Receiver operating characteristic curve (ROC) was drawn to analyze the prognostic value of the above indicators alone or in combination. Data analysis was performed using SPSS statistics 17.0. Depending on the data type, t-test, rank sum test or χ² test is used. Logistic regression was performed to analyze the prognostic value of each predictor. Results The scores of PCT,D-D and SOFA in the septic shock group were significantly higher than those in the sepsis group [PCT(μg/L):7.25 (3.93,10.56) vs 2.55 (1.59,5.45); D-D (mg/L): 5.40 (3.24,6.95) vs 2.59 (1.68,5.61); SOFA:8.0 (6.0,11.0) vs 6.0 (4.0,7.0)],and the differences were statistically significant (P<0.05). The PCT,D-D and SOFA in the death group were significantly higher than those in the survival group [PCT(μg/L):3.94 (2.89,11.36) vs 2.79 (1.67,6.50), D-D (mg/L):4.16 (2.67,7.10)vs 2.88 (1.74,5.82),SOFA:8.0 (7.0,11.0) vs 6.0 (4.0,8.0)],and the differences were statistically significant (P<0.05). The area under the ROC curve(AUC)was 0.657 for PCT,0.633 for D-D,0.715 for SOFA and 0.748 for PCT + D-D + SOFA,indicating that each index was predictive of the 28-day prognosis of the elderly patients with sepsis. The three indexes in combination performed best with a sensitivity of 97.1% and a specificity of 59.8%. Conclusion PCT,D-D and SOFA scores are the predictors of severity and prognosis of the elderly patients with sepsis, and the combination of the three has the highest predictive value.