To further improve the understanding of the effect of T cells on the diagnosis and prognosis of RA, we obtained eight T cell-related diagnostic features by combining machine learning and MR (ICOS, IL6ST and PPP1CB were risk factors for RA, while GADD45A, CD3D, SLFN5, PIP4K2A and MIER1were protective factors for RA), which were constructed a T cell-related diagnostic model. This evidence concerns the gene ICOS and rheumatoid arthritis.