Objective To explore the mechanism of heat shock factor (HSFl) alleviating coagulatory dysfunction in sepsis and protecting mice from acute lung injury.Methods In this study, a mouse model of sepsis was established by cecal ligation and puncture (CLP). We tested the coagulation indexes and pathological changes in the lungs of mice. Protein C expression was detected by ELISA, qRT-PCR and Western blotting. The expression level of protein C was observed by inhibiting or enhancing the expression of HSF1 by plasmid transfection, and the mechanism of HSF1 regulating protein C transcription was explored by bioinformatics, EMSA and dual luciferase reporter gene experiments.Results In the mouse model of sepsis, we discovered that the coagulatory activity of the HSF^-/- mice was significantly enhanced and the lung injury was aggravated after CLP, compared with the HSF1^+/+ mice. ELISA, qRT-PCR and Western blot showed that the expression level of protein C in the plasma and lung tissue of the HSF^-/- mice was lower than that in the wild-type mice in sepsis. In vitro studies also demonstrated that HSF1 interference inhibited lipopolysaccharide (LPS)-induced protein C expression, while HSF1 overexpression enhanced protein C expression in bEnd.3 vascular endothelial cells. Further bioinformatics analysis indicated that the protein C promoter region contains HSF1 binding element (HSE). EMSA and dual luciferase reporter gene experiments showed that HSF1 bound to the HSE in the promoter region of protein C, thereby directly upregulating protein C transcription.Conclusion This study revealed that HSF1 was involved in acute lung injury in sepsis mouse model. HSF1 alleviated the coagulatory dysfunction in sepsis by directly upregulating protein C transcription, thus playing a protective role in mouse lung tissue.