Objective To study the therapeutic effect of rapamycin (RAPA) on experimental autoimmune myasthenia gravis (EAMG) rats and to explore the related immune mechanisms. Methods The mouse-derived acetylcholine receptor alpha subunit 97-116 peptide (R97-116) was used to immunize Lewis rats to establish an EAMG rat model. The rats were randomly divided into three groups: complete Freund's adjuvant control group (CFA group), EAMG model control group, and RAPA treatment group [1 mg/(kg.d)]. The Lennon muscle strength scoring scale was used to evaluate rats' clinical symptoms in each group once every two days, and their body mass was recorded. ELISA was performed to detect the level of anti-R97-116 antibodies in the peripheral blood of rats. Flow cytometry was used to detect the numbers of Th17 cells and regulatory T cells (Tregs) in rat splenocytes. Splenocytes were stimulated with 5 μg/mL concanavalin A (ConA), 10 μg/mL R97-116 and RPMI1640 medium, and the proliferation activity of rat splenocytes was tested by CCK-8 assay. Results RAPA treatment significantly improved the body mass and clinical scores in EAMG rats. Compared with the CFA group, the number of Th17 cells in the spleen of the EAMG group increased, and the number of Tregs decreased. Compared with the EAMG group, the number of Th17 cells in the spleen of RAPA-treated rats significantly dropped, the number of Tregs went up, and the level of anti-R97-116 antibodies in the serum went down. RAPA treatment inhibited the proliferation of lymphocytes induced by RPMI1640 medium, R97-116, and ConA stimulation. Conclusion RAPA may alleviate the clinical symptoms of EAMG rats by down-regulating the ratio of Th17 cells/Tregs.