Background and Objective: Immune thrombocytopenia (ITP) is an autoimmune-mediated hemorrhagic disease. Anti-glycoprotein autoantibodies play a key role in the pathophysiology of ITP, but the relationship between platelet-specific antibodies and bleeding severity is unclear. This study aimed to analyze the relationship between anti-glycoprotein autoantibodies and bleeding severity in children with newly diagnosed ITP and platelet count <10×109/L. Method: This was a single-center prospective observational study that analyzed children with newly diagnosed ITP and platelet count <10×109/L between June 2018 and September 2021 at our hospital. The children were classified into the mild and severe groups based on the bleeding scores. The type and titer of anti-glycoprotein autoantibodies were detected using an ELISA kit (PAKAUTO). We analyzed the relationship between bleeding severity and anti-glycoprotein autoantibodies. Results: A total of 86 cases were enrolled, including 42 in the mild group and 44 in the severe group. Patients with anti-GPIIb/IIIa or anti-GPIb/IX antibodies suffered more severe bleeding than patients without them (c2=7.303, p=0.007; c2=3.875, p=0.049), but there was no significant difference between patients with or without anti-GPIa/IIa antibody (c2=0.745, p=0.388). When antibodies were analyzed together, patients with three antibodies suffered more severe bleeding than those without three antibodies (c2=5.053, p=0.025). Patients with higher antibody titer in the eluent, but not in the plasma, suffered more severe bleeding in all three antibodies (Z=-2.389, p=0.017; Z=-2.108, p=0.035; Z=-2.557, p=0.011). Conclusion: Anti-glycoprotein autoantibodies led to more severe bleeding in children under 18 years of age without drug treatment with newly diagnosed ITP and platelet count <10×109/L.