ObjectiveTo analyze the change in immune function and therapeutic effectiveness of children with immune thrombocytopenic purpura and Helicobacter pylori（H. pylori） infection. MethodsEighty hospitalized children with thrombocytopenic purpura between March 2011 and March 2012 were as observation group, and then subdivided into infected group and noninfected group according to whether they were infected with H. pylori; 80 healthy children were as control group . Lymphocyte subsets , clinical therapeutic effectiveness and recurrence rate among three groups were compared. ResultsThe positive rate of H. pylori in observation group was significantly higher than control group( 55.00% ［44/80］ vs 2.50% ［2/80］; χ2=12.48，P=0.008）. There was significant differences in CD4+, CD4+/CD8+ ,and CD19+T lymphocyte among three groups （all P＜0.05）;  CD4+  and  CD4+/CD8+ T lymphocyte in infected group was significantly lower than noninfected group respectively  (［13.40±4.65］%) vs ［28.56±3.82］%; ［0.69±0.18］% vs ［1.04±0.23］%) , and CD19+T lymphocyte in infected group was significantly higher than noninfected group  (［45.21±10.20］% vs ［22.05±2.23］%) ; CD4+ and CD4+/CD8+T lymphocyte in noninfected group and infected group was significantly lower than control group (［40.20±3.42］%  ,［1.54±0.42］% respectively), and CD19+T lymphocyte was significantly higher than control group (［11.02±2.89］%) . The overall therapeutic effectiveness in infected  group and noninfected group was 90.91% and 91.67% respectively（P＞0.05） . The recurrence rate of thrombocytopenic purpura after antiH.pylori infection therapy in  infected group was significantly lower than noninfected group （20.45% vs 30.56%；χ2=6.396，P=0.038）. ConclusionDetection of immune function is helpful for clinical diagnosis of H. pylori infection associated with immune thrombocytopenic purpura .