〔Abstract〕 Objective To study the serum interleukin-6 concentration and phenotypes and phagocytosis of neutrophils for the diagnosis and staging of sepsis. Methods A total of 121 patients were collected between January 2018 and June 2019. The patients were divided into two groups: the group of systemic inflammatory response syndrome(SIRS, 95 cases,including 19 cases of non-sepsis, 56 cases of sepsis and 20 cases of septic shock), the group of local infection(26 cases). Meanwhile, 20 cases of healthy volunteers were selected as the control group. Cytokines(IL-2, IL-4, IL-6, IL-10, IFN-γ, TNF-α), PCT, hsCRP, and WBC counts were measured, and the phenotypes(CD64, CD11 b and CD62 L) of peripheral blood neutrophils(PBNs) and their phagocytic function were determined. Results The levels of serum IL-6 and IL-10 were found to be highest in the patients of SIRS group(P<0.01), followed by those of the local infection group and the control(P<0.01). The patients of septic shock had the highest level of serum IL-6(P<0.01), followed by those of septic group and non-septic group(P<0.01), but no significant difference of IL-10 levels was noted between the groups of septic shock and sepsis(P>0.05). Compared with those of low IL-6 concentration in the groups, patients with high serum IL-6 level simultaneously presented elevated levels of hs-CRP, PCT and IL-10(P<0.01), accompanied by increased expressions of CD11 b and CD64(P<0.01). Additionally, the PBNs phagocytosis was found to be enhanced in the patients of high IL-6 level when compared with those of low IL-6 level(P<0.01). Conclusion The serum level of IL-6 in the patients with sepsis gradually increased as the disease progresses, and the highest level of serum IL-6 may be noted in the patients with sepsis shock, followed by those of sepsis and non-sepsis consecutively. An elevated level of serum IL-6 was frequently accompanied by enhanced neutrophil phagocytosis and high expressions of CD64 and CD11 b in the patients with sepsis. Taken together, examination of serum IL-6, which is closely associated with clinical stages of sepsis, is quite valuable for diagnosis of the disease. Thus tracking and monitoring of serum IL-6 may provide a reference for the clinical diagnosis and progress of sepsis, worth being promoted practically.