Abstract： Objective:To investigate the potential causal effects of six autoimmune diseases (rheumatoid arthritis [RA], systemic lupus erythematosus [SLE], ankylosing spondylitis, type 1 diabetes mellitus, inflammatory bowel disease and psoriasis) on tuberculosis.Methods:Based on the large-sample genome-wide association studies summary data, a two-sample Mendelian randomization (MR) analysis via the inverse variance weighting (IVW), weighted median, and MR-Egger regression was applied.In this study, IVW was used as the main analytical method and the other two methods were used as further validation, while sensitivity analyses such as horizontal pleiotropy test, heterogeneity test and leave-one-out test were conducted to test the reliability of the results.Results:RA and SLE presented a positive causal relationship with tuberculosis ( ORRA=1.08, 95% CIRA: 1.01-1.14, PRA=0.023; ORSLE=1.06, 95% CISLE: 1.02-1.20, PSLE=0.002).WME results supported a causal association between RA and tuberculosis ( ORRA=1.12, 95% CIRA: 1.04-1.21, PRA=0.002; ORSLE=1.05, 95% CISLE: 0.99-1.10, PSLE=0.096).However, the results of the MR-Egger method were not statistically significant ( PRA=0.062, PSLE=0.205).The other four autoimmune diseases were not found to be causally associated with tuberculosis (all P>0.05).The results of the sensitivity analyses showed no pleiotropy or heterogeneity in all the results, and the leave-one-out method also suggested that the results obtained were robust. Conclusion:There is a positive causal relationship between RA, SLE and tuberculosis, patients with RA and SLE are at increased risk of tuberculosis.