Objective To analyse the correlation of between early WBC、PCT、CRP、IL-2、IL-4、IL-6、IL-10、TNF-α、IFN-γ、PLT、Lym and severity and prognosis in elderly patients with sepsis. Methods Retrospective analysis of the clinical data of 135 sepsis patients admitted to the Geriatric ICU in Jiangsu Province Hospital from September 2020 to March 2022. According to age, patients were divided into the elderly group (≥ 65 years old) and the young adult group (<65 years old); The elderly patients with sepsis were divided into septic shock group and septic group according to whether they were septic shock, and into survival group and death group according to the 28-day mortality rate. The above groups compare WBC、PCT、CRP、IL-2、IL-4、IL-6、IL-10、TNF-α、IFN-γ、PLT、Lym、APACHE II score in pairs. To analyse the correlations between WBC、PCT、CRP、IL-2、IL-4、IL-6、IL-10、TNF-α、IFN-γ、PLT、Lym and APACHE II score in elderly patients with sepsis by Sperman correlation analysis. Through drawing ROC curve to compare WBC、PCT、CRP、IL-2、IL-4、IL-6、IL-10、TNF-α、IFN-γ、PLT、Lym and APACHE II score in the judgement of 28-day mortality rate in elderly patients with sepsis. Results In patients with sepsis, the PLT、Lym in the elderly group were significantly lower than those in the young adult group, and APACHE II score in the elderly group was significantly higher than that in the young adult group. In elderly patients with sepsis, the PCT、CRP、APACHE II score in septic shock group were significantly higher than those in the septic group, and PLT in septic shock group was significantly lower than that in the septic group; and APACHE II score in the survival group was significantly lower than that in the death group; IL-10 is positively correlated with APACHE Ⅱ score, and PLT is negatively correlated with APACHE Ⅱ score. According to ROC curve and area under the curve, the APACHE II score of a single indicator, combination of all indicators except APACHE II score and the combination of all indicators can predict the 28-day mortality rate of elderly patients with sepsis. Conclusion In elderly patients with sepsis, the lower the PLT and the higher IL-10 in the early stage, the worse the condition and prognosis of the elderly patients with sepsis. Combination of multiple indicators to predict 28-day mortality in elderly patients with sepsis has a higher accuracy.