Objective To analyze the distribution characteristics and clinical significance of T lymphocyte subpopulations combined with the neutrophil-to-lymphocyte ratio (NLR) in children with immune thrombocytopenia (ITP). Methods A retrospective study design was adopted. A total of 134 children with ITP who were treated at the First Affiliated Hospital of Xinxiang Medical University and the First People’s Hospital of Pingdingshan City from January 2023 to January 2025 were selected as the study subjects, and 100 healthy children during the same period were selected as the control group. Compare the T lymphocyte subpopulations (CD3+cells, CD3+CD8+cells, CD3+CD4+cells, CD3+CD4-CD8-cells) and the neutrophil-to-lymphocyte ratio (NLR) between the two group. Based on the differences between the two groups, receiver operator characteristic (ROC) curve was plotted to evaluate the predictive efficacy of T lymphocyte subpopulations combined with NLR for ITP. According to the course of disease, the ITP children were divided into newly diagnosed group (first diagnosis, disease duration＜3 months, n＝92), persistent group (disease duration 3-12 months, n＝8), and a chronic group (disease duration＞12 months, n＝34). The T lymphocyte subpopulations and NLR values were compared among the three groups. Results The CD3+ cells and CD3+CD4+ cells in the ITP group were lower than those in the control group (all P＜0.05), while the CD3+CD8+ cells, CD3+CD4-CD8- cells, and NLR in the ITP group were higher than those in the control group (all P＜0.05). The combined predictive efficacy of T lymphocyte subpopulations and NLR for ITP was higher than that of any single indicator (all P＜0.05). Among ITP children with different disease durations, only CD3+ cells and NLR showed statistically significant differences between groups (all P＜0.05). Specifically, the newly diagnosed group had higher CD3+ cells than the persistent group (P＜0.05), and the chronic group had higher NLR than the newly diagnosed group (P＜0.05). The sample size of the persistent group was small, with limited statistical power, so the relevant results need to be interpreted with caution. Conclusion Children with ITP exhibit pathological states of disordered T lymphocyte subpopulation distribution and high NLR expression. Combining these two indicators can enhance the efficacy of auxiliary diagnosis and risk prediction for ITP.