Objective To investigate the effects of phototherapy on the cognitive function in patients with Alzheimer′s disease (AD), providing reference for improving cognitive outcomes in this population. Methods A computerized search was conducted across PubMed, Cochrane Library, Web of Science, Embase, China National Knowledge Infrastructure (CNKI), Wanfang Data, VIP Database, and SinoMed for studies evaluating the impact of phototherapy on cognitive function in AD patients. Two researchers independently screened the literature based on predefined inclusion/exclusion criteria, assessed study quality, and extracted data. Statistical analysis was performed using RevMan5.4 software. Results A total of ten randomized controlled trials (RCTs) were included for quantitative synthesis. The results demonstrated that phototherapy significantly improved Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores in AD patients (both P<0.05), though no significant difference was observed in Alzheimer′s Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) scores before and after intervention. Subgroup analysis revealed that phototherapy with the following parameters yielded notable cognitive improvements:single-session duration <30 minutes, weekly cumulative exposure <2 hours, and near-infrared spectrum (all P<0.05). Conclusion Phototherapy may enhance cognitive function in AD patients, particularly with shorter session durations and near-infrared wavelengths. However, optimal light intensity and treatment frequency require further investigation.