Objective: To investigate the efficacy and safety of iguratimod combined with tofacitinib in patients with difficult-to-treat moderate-to-severe rheumatoid arthritis (RA). Methods: In this prospective clinical study, 30 patients with difficult-to-treat moderate-to-severe RA who attended the Department of Rheumatology and Immunology of Shanxi Province Fenyang Hospital from September 2021 to June 2022 were selected. Twenty-three patients enrollment had been treated with 2 or more conventional synthetic disease modifying anti-rheumatic drugs (DMARDs) for more than 6 months. At least, methotrexate or leflunomide was included. Seven patients were treated with conventional synthetic DMARDs combined with tumor necrosis factor antagonists. Because all the patients had not reached the target of treatment, the combination treatment regimen of DMARDs was changed to iguratimod and tofacitinib. The observation period was 12 weeks. Clinical data were collected before and after treatment. At the end of 4 weeks, 8 weeks and 12 weeks, the clinical data were collected such as swollen joints count (SJC), tender joints count (TJC), time of morning stiffness, clinical disease activity index (CDAI), health status assessment questionnaire (HAQ), and 28-joint disease activity score (DAS28) were included. We collected laboratory indicators, recorded the patient's medication, and observed some changes to see if any adverse drug reactions occurred during the treatment. Results: There were significant differences in erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), rheumatoid factor (RF), platelet (PLT), SJC, TJC, DAS28 based on ESR(DAS28-ESR), time of morning stiffness, HAQ, CDAI, and anti-cyclic citrullinated peptide antibody before and after treatment. The differences had statistical significance (P < 0.05). There was no statistical differences in globulin before and after treatment (P>0.05). During the treatment of iguratimod combined with tofacitinib, there was no serious adverse reactions such as leukopenia, significant elevation of liver enzymes, allergy or thromboemblolic events that occurred in all the patients. Conclusion: Iguratimod combined with tofacitinib in the treatment of difficult-to-treat moderate-to-severe RA may have efficacy. The machanism was improving the patients' recent clinical symptoms by reducing inflammatory indexes. This combination treatment regimen with iguratimod and tofacitinib has a good safety profile.