Objective To investigate the effects of Protosappanin A (PrA) on sepsis-induced myocardial injury and explore its potential mechanism. Methods The sepsis-induced myocardial injury model was established by cecal ligation and puncture (CLP). Sixty male C57BL/6 mice were randomly divided into four groups: sham+saline group、sham+PrA group、CLP+saline group and CLP+PrA group, with 15 mice in each group. CLP operation was performed in CLP+saline group and CLP+PrA group, while sham operation was performed in sham+saline group and sham+PrA group. sham+PrA group and CLP+PrA group were given intraperitoneal injection of PrA (20 mg/kg) once each at 1 day before surgery and at 6 h and 12 h after surgery. After 24 hours, left ventricular ejection fraction (LVEF) and left ventricular shortening fraction (LVFS) were measured using cardiac ultrasonography and the blood and myocardial tissue were collected. Serum creatine kinase isoenzyme (CK-MB), lactate dehydrogenase (LDH) and cardiac troponin I (cTnI) were detected by ELISA kits. The mRNA expressions of IL-1β, IL-6 and TNF-α were detected by qRT-PCR. The protein expressions of NLRP3, ASC, Cleaved caspase-1, IL-1β, IL-18, N-GSDMD, TLR4, MyD88 and p-NF-κB p65 were detected by Western blotting. Results Compared with sham+saline group, the values of LVEF and LVFS in CLP+saline group were decreased (P＜0.05), the serum levels of CK-MB, LDH and cTnI were increased (P＜0.05), the mRNA expressions of IL-1β, IL-6, and TNF-α were increased (P＜0.05), the protein expressions of NLRP3, ASC, Cleaved caspase-1, IL-1β, IL-18, and N-GSDMD were up-regulated (P＜0.05) and the TLR4/MyD88/NF-κB pathway was significantly activated in CLP+saline group (P＜0.05). Compared with CLP+saline group, the values of LVEF and LVFS in CLP+PrA group were increased (P＜0.05), the serum levels of CK-MB, LDH and cTnI were decreased (P＜0.05), the mRNA expressions of IL-1β, IL-6, and TNF-α were decreased (P＜0.05), the protein expressions of NLRP3, ASC, and Cleaved caspase-1, IL-1β, IL-18, and N-GSDMD were down-regulated (P＜0.05), and the TLR4/MyD88/NF-κB pathway was significantly inhibited (P＜0.05).Conclusion PrA inhibits cardiomyocyte pyroptosis and myocardial inflammation by regulating the TLR4/MyD88/NF-κB signaling pathway, thereby alleviating myocardial damage caused by sepsis