Abstract: Abstract：This study aimed to systematically explore the regulatory effect and molecular mechanism of linalyl acetate on immune function in mice, so as to provide experimental basis for developing new green immunomodulators in animal husbandry production. Thirty-two 30-day-old SPF C57BL/6 male mice were randomly divided into control group (gavaged with normal saline), low-dose group (50 mg/kg linalyl acetate), medium-dose group (100 mg/kg linalyl acetate) and high-dose group (200 mg/kg linalyl acetate), with continuous gavage for 28 days. The dynamic changes of body weight were detected, and the thymus and spleen indices were calculated; the pathological morphological structures of immune organs (thymus, spleen) and intestinal mucosa (duodenum) were observed by HE staining; the expression levels of IgA, IgM and IgG immune-related genes in spleen and thymus tissues were quantitatively analyzed by qPCR. The results showed that there was no significant difference in body weight growth trend between each dose group and the control group (P>0.05), and no growth inhibition was observed; the spleen indices of the medium-dose group (0.31±0.02) and high-dose group (0.33±0.02) were significantly higher than that of the control group (0.26±0.01) (P<0.05), and the thymus index showed a dose-dependent increasing trend but no statistical difference (P>0.05); HE staining showed that the boundary between cortex and medulla of thymus was clear in each dose group, the white pulp and red pulp of spleen were intact, the villi of duodenal mucosa were arranged neatly, and there was no inflammatory infiltration or tissue damage; qPCR results showed that the expression levels of IgA (1.89±0.12, 2.35±0.15), IgM (1.76±0.10, 2.18±0.13) and IgG (1.92±0.11, 2.41±0.14) in the spleen of the medium and high-dose groups were significantly higher than those of the control group (P<0.01), and the expression levels of the above genes in the thymus were also upregulated in a dose-dependent manner (P<0.05 or P<0.01). Conclusion: Linalyl acetate has no obvious toxicity to mice in the dose range of 50-200 mg/kg, and can enhance humoral immune function by promoting the development of immune organs and upregulating the expression of immune globulin genes, which has potential application value as an immunomodulator in animal husbandry production.