Background: Purpuric nephritis is the most common secondary glomerular disease in childhood. Its prevalence in children has been steadily rising in recent years. Objective: To explore the characteristics and pathogenesis of changes in peripheral blood lymphocyte subsets and immune function in children with Henoch-Schonlein purpura nephritis. Methods: The study included 104 children with Henoch-Schonlein purpura, divided into nephritis (HSPN) group (68 cases) and non-nephritis (NHSPN) group (36 cases), and 15 normal children. The rate-scatter turbidimetric method was utilized to determine the immunoglobulins IgA, IgG, IgM, C3 and C4, and the flow cytometry technique was employed to detect the levels of lymphocyte subsets including CD3+, CD4+, CD8+, CD4+/CD8+, CD19+, NK, etc. Results: Compared with the control group, the CD3+, CD4+, CD8+ and NK cell levels of peripheral blood mononuclear cells significantly decreased (p <0.05), and the CD19+ level significantly elevated (p <0.05) in the HSPN group and the NHSPN group whereas the HSPN group had a more significant change than the NHSPN group (p <0.05). Compared with the control group, the serum immunoglobulin IgA and IgG of the HSPN group and the NHSPN group significantly increased, and the IgM, C3, and C4 significantly decreased (p <0.05); while the HSPN group had a more significant change than the NHSPN group (p <0.05). Conclusion: Immune dysfunction in children with HSPN is specifically manifested as low cellular immune function, which leads to increased secretion of inflammatory mediators, activates B cells, and further increases the secretion of immunoglobulins, leading to the occurrence of small vasculitis.