Objective: To investigate the expression of T cell subsets in the spleen of BTBR T+Itpr3tf autistic mouse at 4, 8, and 12 weeks of age, and to determine the optimal age for studying the relationship between immune abnormalities and autism in BTBR autistic mice. Methods: It randomly selected 5-6 male BTBR mouse at 4 weeks, 8 weeks, and 12 weeks of age and C57 mouse of the same gender at corresponding ages for the three-box social interaction test, the self-grooming test, and the marble-burying test; Single cell suspensions were prepared from the spleens of mouse at 8 and 12 weeks of age, and flow cytometry was used to detect 8 subsets of T cells (TH1, TH2, TH17, TC1, TC2, TC17, TFH, and Treg). Results: Compared with C57 mouse of the same age,p＜0.05， BTBR mouse at 4 weeks, 8 weeks, and 12 weeks of age showed a decrease in social time（p＜0.0001，p＜0.0001，p＜0.0001）, an increase in grooming time（p=0.004，p=0.0001，p＜0.0001）, and an increase in the number of marbles buried（p=0.001，p＜0.0001） in BTBR mouse at 8 weeks and 12 weeks of age; As well , the expression of TH1（p=0.0001）, TH2p=0.006）, TC1（p=0.026）, TC2（p=0.0001）, and TFH（p=0.001）cells in 8-week-old BTBR mouse were significantly increased, while the expression of Treg（p=0.0001） cells were significantly decreased; The expression of TH1（p=0.002）, TH2（p=0.009）, TH17（p=0.016）, TC1（p=0.001）, TC2（p=0.0001）, TC17（p=0.005）, and TFH （p=0.0001）increased in 12-week-old BTBR mouse, while the expression of Treg （p=0.01）cells decreased. At different age stages, p＜0.05,the ratio of TH1/Treg and TC1/Treg in 8-week-old BTBR mouse were significantly higher than those in 12 week old mouse, while the TC17/Treg ratio decreased. Conclusions: BTBR mouse at different developmental stages exhibit varying degrees of abnormal increase in Teff/Treg ratio; Based on results of behavioral test, it is recommended to use 8-week-old BTBR mice for research on autism and immune abnormalities.