Objective To analyze the trends and influencing factors of rheumatoid arthritis disease burden in mainland China from 1990 to 2021 and predict its disease burden over the next 15 years. MethodsData on RA incidence, prevalence, mortality, and disability-adjusted life years (DALYs) in mainland China were extracted from the Global Burden of Disease Study 2021 (GBD 2021). Joinpoint regression was used to analyze temporal trends, while an age-period-cohort model assessed age, period, and birth cohort effects. Decomposition analysis explored the contributions of population aging, population growth, and epidemiological changes. An ARIMA model was applied to predict future disease burden. ResultsFrom 1990 to 2021, the number of RA cases in mainland China increased by 93.5% (incidence), 133% (prevalence), 115% (deaths), and 107% (DALYs), though age-standardized rates showed smaller changes. The disease burden was significantly higher in women than in men, with sex-specific peaks in onset and prevalence. Joinpoint regression revealed rising age-standardized incidence and prevalence rates (AAPC=0.54% and 0.51%, respectively) but declining mortality (AAPC=−0.78%). Cohort effects indicated higher RA risk in later-born populations (RR=1.53 for the 2012 cohort). Decomposition analysis identified population growth as the primary driver of increased burden. Projections suggested that by 2036, the age-standardized incidence and prevalence would rise to 13.92/100 000 and 248.84/100 000, respectively, while DALYs rates might decline to 42.09/100 000. ConclusionThe RA disease burden in mainland China is driven by both population aging and epidemiological factors, with notable sex disparities and cohort effects. Targeted interventions for high-risk populations, optimized healthcare resource allocation, and further research on influencing factors are needed to develop precise prevention and control strategies.