OBJECTIVE To comprehensively evaluate the efficacy， safety， and cost-effectiveness of lecanemab in the treatment of early-stage Alzheimer’s disease （AD）， and to provide evidence-based guidance for clinical decision-making. METHODS A systematic search of PubMed， Cochrane Library， CNKI， Wanfang， Embase， and the official websites of leading health technology assessment （HTA） agencies was conducted for randomized controlled trials， pharmacoeconomic studies， meta-analyses/systematic reviews， and HTA reports on lecanemab published up to October 2025. After screening against predefined eligibility criteria， methodological quality was appraised with validated tools， relevant data were extracted， and the findings were synthesized qualitatively. RESULTS A total of 6 studies were included， consisting of 3 randomized controlled trials and 3 pharmacoeconomic evaluations. In terms of efficacy， lecanemab significantly slowed cognitive decline by 27% compared to placebo， reduced the decline in daily activity ability by 37%， and markedly reduced intracerebral amyloid levels. Regarding safety， the incidence of amyloid-related imaging abnormalities （ARIA） was higher in the lecanemab group than in the control group， with the incidence of edema/effusion of 12.6% （vs. 1.7% in the placebo group）， and the incidence of hemorrhage/hemosiderin deposition of 17.3% （vs. 9.0% in the placebo group）. Economically， the estimated incremental cost-effectiveness ratio of lecanemab compared with standard treatment exceeded commonly used willingness-to-pay thresholds in the United States （USD 50 000-150 000 per QALY）. CONCLUSIONS Lecanemab confers significant cognitive protection in early-stage AD； however， it is associated with a relatively high risk of ARIA and economic burden.