Abstract: Objective To explore the mechanism by which tanshinone ⅡA (Tan ⅡA) improves lipopolysaccharide (LPS)-induced myocardial cell injury. Methods An in vitro model of septic myocardial injury was established using LPS. H9C2 myocardial cells were divided into the following groups: a Control group, a LPS group (treatment with LPS at 25 mg/L), a Tan ⅡA-L group (LPS + 5 μmol/L Tan ⅡA), a Tan ⅡA-M group (LPS+10 μmol/L Tan ⅡA), a Tan ⅡA-H group (LPS+20 μmol/L Tan ⅡA), and a Tan ⅡA-H-CC group (LPS+20 μmol/L Tan ⅡA+10 μmol/L AMPK pathway inhibitor Compound C). The cell survival rate was measured by CCK-8 assay. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), and lactate dehydrogenase (LDH) were determined using assay kits. The levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) in cell culture supernatant were detected by ELISA. The levels of AMP-activated protein kinase (AMPK), phosphorylated AMP-activated protein kinase (p-AMPK), and suppressor of cytokine signaling 3 (SOCS3) proteins were measured by Western blot. Results Compared with the Control group, there were no statistical differences in myocardial cell survival rate among the Tan ⅡA treatment groups (5, 10, and 20 μmol/L Tan ⅡA) (P>0.05). Compared with the Control group, the LPS group showed decreases in cell survival rate and increases in MDA, SOD, LDH, IL-1β, IL-6, and TNF-α levels, with a reduction in the expression of p-AMPK and SOCS3 proteins (P<0.05). Compared with the LPS group, the Tan ⅡA-L, Tan ⅡA-M, and Tan ⅡA-H groups exhibited increased cell survival rate, decreased levels of MDA, SOD, LDH, IL-1β, IL-6, and TNF-α and elevated expression of p-AMPK and SOCS3 proteins in a dose-dependent manner (P<0.05). The AMPK pathway inhibitor reversed the effect of Tan ⅡA on LPS-induced myocardial cell survival rate, as well as the levels of MDA, SOD, LDH, IL-1β, IL-6, and TNF-α, and down-regulated the expression of p-AMPK and SOCS3 proteins. Conclusions Tan ⅡA improves LPS-induced myocardial cell injury, which may be related to the up-regulation of the AMPK/SOCS3 signaling pathway, thereby reducing oxidative stress damage and inflammatory responses.