Objective To investigate the relationship between peripheral T lymphocyte subgroup and complications in patients with scrub typhus. Methods A total of 53 patients with scrub typhus treated in Ruijin People's Hospital from January 2018 to September 2021 and 50 healthy people took physical examination in the same period were selected as the research objects.Then establish the observation group and the control group.Observation group 1 contains 53 patients with scrub typhus. Control group 1 contains 50 healthy people. Observation group 2 contains 37 patients with complications of scrub typhus (including 10 cases in single organ damage group, 14 cases in double organ damage group and 13 cases in multiple organ damage group). Control group 2 contains 16 patients without complications of scrub typhus.CD3+, CD4+, CD8+ T lymphocytes, CD4+/CD8+ ratio were observed before and after treatment in patients with/without complications and healthy people. Results The number of CD3+, CD4+, CD8+ T lymphocyte and CD4+/CD8+ ratio of observation group 1 were lower than those of control group 1,the differences were statistically significant(P<0.05).The above indicators of observation group 1 were higher than those before treatment, the differences were statistically significant(P<0.05). There were no significant differences in the above indexes between observation group 2 and control group 2 before treatment (P>0.05). There was no significant differences in the above indexes between the single organ damage group and the control group 2 (P>0.05). The number of CD3+T lymphocytes and CD4+/CD8+ ratio in the double organ damage group and multiple organ damage group were lower than those in the control group 2, the differences were statistically significant (P<0.05). The number of CD4+T lymphocytes in the double organ damage group was higher than that of control group,the difference was statistically significant (P>0.05). Conclusion T lymphocyte subgroup participates in the pathogenesis of scrub typhus, cellular immune dysfunction plays an important role in the pathogenesis of scrub typhus, and early diagnosis and treatment can better protect the cell immunity of scrub typhus patients, reduce the occurrence of complications and improve the prognosis.