Objective To clarify the effect of aluminum exposure on the cognitive function in electrolytic workers and the prevalence of mild cognitive impairment (MCI) among them by prevalence survey,and to investigate its influential factors.Methods Sixty-six retired workers from the electrolysis workshop of an electrolytic aluminum plant were selected as an aluminum exposure group,while 70 retired workers from a flour mill in the same region were selected as a control group.MCI patients were screened out by Mini-Mental State Examination (MMSE); the blood aluminum level was measured by inductively coupled plasma-mass spectrometry; multivariate statistical analysis was used to investigate the influential factors for MMSE scores and the correlation between blood aluminum level and MCI prevalence.Results The aluminum exposure group showed a significantly higher blood aluminum level than the control group (25.18±2.65 μg/L vs 9.97 ±2.83 μg/L,P＜0.01).The total MMSE score of the aluminum exposure group (26.13±2.57) was significantly lower than that of the control group (27.89± 1.91) (P＜0.05),particularly the scores on time and place orientation,short-term memory,calculation ability,and language skill (P＜0.05).The detection rate of MCI was significantly higher in the aluminum exposure group (18.2％) than in the control group (5.7％) (P＜0.01).The main influential factors for MMSE scores were gender,age,education level,and blood aluminum level.The logistic regression analysis indicated that the MCI prevalence was significantly correlated with blood aluminum level in the study population (OR=1.168,P＜0.01).Conclusion Long-term exposure to aluminum can cause cognitive disorders in electrolytic workers and may be one of the risk factors for MCI.Advanced age,male,low education level,and high blood aluminum level may be high-risk factors for cognitive impairment.