In this study, CD19 CAR-T cells were administered to patients with relapsed/refractory autoimmune diseases. This study intends to use retroviral vector-based tandem CAR-T cells targeting CD19 to treat autoimmune disease. The CAR-T cells were provided by Shenzhen Cell Valley. A study published in the New England Journal of Medicine provides strong evidence for the therapeutic potential of CD19 CAR-T therapy in autoimmune diseases. The study enrolled 15 participants, including eight with severe SLE, three with idiopathic inflammatory myositis, and four with systemic sclerosis. The median follow-up was 15 months (4 to 29 months). Data from the clinical trial showed that all patients with SLE had a remission of DORIS, all patients with idiopathic inflammatory myositis had an ACR-EULAR major clinical response, all patients with systemic sclerosis had a decrease in the EUSTAR activity index score, and all patients discontinued immunosuppressive therapy completely. The investigators look forward to expanding the use of CAR-T cells in relapsed/refractory autoimmune diseases through this safety and efficacy clinical study and greatly enhancing the quality of life for these patients.