Abstract: OBJECTIVE To preliminarily explore the protective effect of betaine on hearts of the mice with sepsis and observe the potential anti-inflammatory mechanisms. METHODS The sepsis mice models were constructed by cecal ligation and puncture (CLP). The male C57BL/6 mice were randomly divided into 5 groups， the survival rate was detected for 20 mice of each group， and the rest of indicators were detected for 10 mice of each group， including the sham surgery group (Ctrl)， the sepsis model group (CLP)， and the sepsis plus low-dose， medium-dose and high-dose Bet intervention groups (CLP+Bet-L， 50 mg/kg; CLP+Bet-M， 100 mg/kg; CLP+Bet-H， 200 mg/kg). The intervention group was treated with abdominal injection of Bet 1 hour before the modeling and was given additional booster injections to maintain the therapeutic effect after the surgery for 24， 48， and 72 hours. The cardiac function， serum creatine kinase MB (CK-MB) level， pathological characteristics of myocardial tissues and expression of inflammatory factor mRNA were detected respectively at certain time points after the modeling. The survival rates of the mice were observed for 7 consecutive days. RESULTS The 7-day survival rate of the mice was lower in the CLP group than in the control group; the cardiac function indicators such as left ventricular ejection fraction (LVEF) and ratio of early to late diastolic blood flow velocity at the mitral valve orifice (E/A) were lower in the CLP group than in the control group; the serum CK-MB level and the expression levels of myocardial tissue interleukin (IL)-6， tumor necrosis factor-α(TNF-α) and IL-1β mRNA were higher in the CLP group than in the control group (all P＜0.05). The mice of the CLP group had myocardial inflammatory infiltration and pathological damage. The Bet intervention groups had the higher survival rate， more improve cardiac function， lower CK-MB level and expression levels of proinflammatory factors， and milder pathological damage of myocardial tissues than the CLP group did， and the improvement effect was dose-independent (P＜0.05). CONCLUSIONS Bet improves the cardiac function and raises the survival rate of the mice by inhibiting the excessive myocardial inflammatory response of the mice， reducing the release of inflammatory factors and myocardial damage. The protective effect is dose-independent.