Objective：To study the variation of Th1/Th17/Th9 cells which produce cytokines and to explore the correlation between these cells and pathogenesis of experimental autoimmune myasthenia gravis（EAMG） young mice after being treated with dual ana－logue（Lys262-Ala207） to create immune tolerance effect through nasal mucosa. Methods：Thirty young C57BL/6 female rats were ran－domized into three groups：model group，tolerance group and control group. Rats in model group were injected with 0.2 ml Ringer’s containing mAb35（1.0 mg/kg） to establish EAMG model；rats in tolerance group were given Lys262-Ala207 intranasally for ten successive days before immunization then were injected 0.2 ml Ringer’s containing mAb35（1.0 mg/kg）；rats in control group were intraperi－toneally injected 0.2 ml Ringer’s without containing mAb35（1.0 mg/kg）. Cells of CD4+ IFN-γ+，CD4+ IL-17+ and CD4+ IL-9+，which respectively represent the cells of Th1/Th17/Th9 in spleen cell of young rats were detected by flow cytometry. IFN-γ、IL-17 and IL-9 in supernatant of spleen cell were detected by Antibody-sandwich ELISA. Results：（1）Clinical symptom of myas－thenia was less obvious in control group than in model group and tolerance group and clinical symptom of myasthenia was alleviated in tolerance group than in model group after being given dual analogue. （2）There were significant differences in the content of CD4+ IFN-γ+ among three groups（model group，tolerance group and control group）（P=0.00）；content of CD4+ IFN-γ+ was higher in model group than in the other groups（P=0.00） and content of CD4+ IFN-γ+ was higher in tolerance group than in control group（P=0.00）. （3）There were significant differences in the content of CD4+ IL-17+ among three groups（model group，tolerance group and control group）（P=0.00）；content of CD4+ IL-17+ was higher in model group than in the other groups（P=0.00） and content of CD4+ IL-17+ was higher in tolerance group than in control group（P=0.00）. （4）There were significant differences in the content of CD4+ IL-9+ among three groups（model group，tolerance group and control group）（P=0.00）；content of CD4+ IL-9+ was higher in model group than in the other groups（P=0.00） and content of CD4+ IL-9+ was higher in tolerance group than in control group（P=0.00）. （5）There were significant differences in the content of IFN-γ、IL-17 and IL-9 in supernatant of spleen cell among three groups（model group，toler－ance group and control group）（P=0.00） indicating that the content was higher in model group than in the other groups（P=0.00） and the content was higher in tolerance group than in control group（P=0.00）. Conclusions：Clinical symptom of myasthenia is relieved ef－fectively，content of CD4+ IFN-γ+，CD4+ IL-17+ and CD4+ IL-9+ as well as the content of IFN-γ、IL-17 and IL-9 which lead to sickness of rats is reduced and unbalance of cell of Th1/Th17/Th9 is relieved after young rats being treated with dual analogue（Lys262-Ala207） to create immune tolerance through nasal mucosa. This clarifies the role of dual analogue in the mechanism of immune tolerance of young rats.