Objective:To investigate the CLEC3B protein of differentially expressed proteins(DEPs)in serum of normal persons and patients with sepsis,and explore the possibility that target C-type lectin domain family 3 member B(CLEC3B)protein was used as molecular markers of sepsis.Methods:Peripheral bloods of 10 healthy persons and 18 patients with sepsis were collected,and the data of peripheral serum proteins were collected by data independent acquisition(DIA)method.The data were uploaded to iDEP online platform to analyze the DEPs in peripheral blood of patients with sepsis.Bioinformatics analysis of these DEPs was conducted to screen out the key proteins of sepsis.Enzyme linked immunosorbent assay(ELISA)was used to verify and plot the receiver operating characteristic(ROC)curves of key proteins.Results:A total of 138 differentially expressed proteins(DEPs)were screened out by using proteomics analysis,of which 34 kinds of proteins were significantly down-regulated and 104 kinds of proteins were significantly up-regulated.DEPs mostly concentrated in cellular processes,biological regulation,biological process regulation,participating binding,catalytic activation,molecular function regulation,immune system,signal transduction and so on.A protein-protein interaction network was constructed by DEPs,which screened out the key protein CLEC3B.ELISA results showed that the CLEC3B protein concentration[(297.73±22.00)ng/mL]of patients in the sepsis group was significantly lower than that[(452.42±191.72)ng/mL]in the healthy group,and the difference was statistically significant(t=13.13,P=0.000).The area under curve(AUC)value of ROC curve,sensitivity and specificity of CLEC38 protein were respectively 0.998,97.73%and 100.0%.Conclusion:CLEC3B is significantly decreased in sepsis group,which sensitivity and specificity are high.It can be used as a potentially biological diagnostic biomarker of sepsis.