Objective To explore the effects of heat-inactivated Lactobacillus gasseri TMC0356 on liver lipid metabolism in rats with metabolic syndrome (MS) and its possible mechanism. Methods Sixty male Sprague-Dawley rats were selected. Rats were randomly divided into 5 groups, including control group, MS model group and three TMC0356 test groups (low-, medium- and high-dose groups). The rats in each group were fed with different diets for 7 days, and the liver was dissected and removed after 15 weeks. The mRNA and protein expression levels of peroxisome hyperbioactive receptor-α (PPAR-α), sterol regulatory element binding protein-1c (REBP-1c), fatty acid synthase (FAS) and carnitine lipoacyltransferase-1 (CPT-1) genes in liver were detected. Results There was no significant difference in the mRNA expression of PPAR-α, SREBP-1c or CPT-1 among the five groups (P>0.05). The mRNA expression of FAS in low-dose TMC0356 test group was lower than that in MS model group (P=0.011), medium-dose TMC0356 test group (P=0.042) and high-dose TMC0356 test group (P=0.009). There was no significant difference in the expression of FAS mRNA between other groups (P>0.05). There was no significant difference in the protein expression of PPAR-α, SREBP-1c or FAS among the five groups (P>0.05). The protein expression of CPT-1 in low-dose TMC0356 test group was higher than that in control group (P=0.033) and high-dose TMC0356 test group (P=0.043). There was no significant difference in the protein expression of CPT-1 between the other groups (P>0.05). Conclusion Heat-inactivated Lactobacillus gasseri TMC0356 may improve the symptoms of metabolic disorder in rats by suppressing appetite, improving insulin resistance, and downregulating the expression of key fat metabolism genes such as FAS and SREBP-1c.