<h4>Objective</h4>To investigate the role of vitamin D (VitD), transforming growth factor-β1 (TGF-β1), and regulatory T cells (Treg) in the pathogenesis of primary immune thrombocytopenia (ITP) in children.<h4>Methods</h4>From February 2023 to September 2024, 51 children with ITP and 44 healthy children from the First Affiliated Hospital of Xinxiang Medical College were enrolled. The gene discussed is TGFB1; the disease is autoimmune thrombocytopenic purpura.