Objective To analyze the expression changes of peripheral blood triggering receptor expressed on myeloid cells-1 (TREM-1) during the progression of sepsis, and to explore the utility of soluble TREM-1 (sTREM-1) and membrane-bound TREM-1 on myeloid cells in disease stratification of sepsis. Methods Sepsis patients, septic shock patients, and healthy controls were enrolled from West China Hospital of Sichuan University between June to December 2022. Membrane-bound TREM-1 expression on peripheral blood myeloid cells was detected by flow cytometry, and serum sTREM-1 levels were measured by enzyme-linked immunosorbent assay. The diagnostic performance of TREM-1-related parameters for discriminating sepsis from septic shock was evaluated by receiver operating characteristic curves. Results A total of 72 samples were collected. Among them, there were 10 healthy controls, 28 sepsis patients, and 34 septic shock patients. Peripheral blood sTREM-1, TREM-1+ granulocytes, and TREM-1+ monocytes showed significant differences among the sepsis, septic shock, and healthy control groups (P<0.05). For discriminating sepsis from septic shock, sTREM-1 yielded a sensitivity of 62.1% and a specificity of 88.9%; TREM-1+ granulocytes had a sensitivity of 65.5% and a specificity of 77.8%; and TREM-1+ monocytes had a sensitivity of 65.5% and a specificity of 66.7%. The combined model of the three indicators generated a predicted probability with an area under the curve of 0.881 [95% confidence interval (0.785, 0.978)], a sensitivity of 93.1%, and a specificity of 66.7%. Conclusions The expression of membrane-bound TREM-1 on peripheral blood granulocytes and monocytes, as well as serum sTREM-1, differs during sepsis progression and demonstrates auxiliary value in identifying disease stratification of sepsis. These parameters may serve as laboratory indicators for assessing the severity of sepsis.