Even though new drugs for the treatment of rheumatoid arthritis (RA) have been developed, methotrexate (MTX) remains a commonly used drug for RA management. In addition to monitoring disease activity during RA treatment, bone erosion should be closely assessed throughout long-term RA management. In this review article, we present a systematic review of MTX effectiveness in reducing the risk of bone erosion. We reviewed randomized controlled trial studies that involved MTX monotherapy or MTX in combination with placebo. Evaluation of the progression of bone erosion was examined by radiographic assessment such as total Sharp score (TSS) or van der Heijde score (SvdH or vdH TSS), joint space narrowing (JSN), erosion score (ERO), and proportion of radiographic nonprogressors. Several key factors were found to influence the response to MTX treatment, such as gene polymorphism. The exact mechanism of the prevention of bone erosion by MTX remains unclear, which warrants future investigations. The variability of RA disease activity in study subjects resulted in variations in the results reported by individual studies. Collective analysis suggests that MTX could slow down the progression of bone erosion based on a radiographic score of less than 0.5–1/year.