Objective To investigate the relationship between serum potassium levels and nutritional status of alcohol dependence patients in psychiatric departments. Methods A total of 213 alcohol-dependent patients admitted to the Mental Health Center of the First Hospital of Hebei Medical University from July 2016 to June 2019 were selected. Patients were screened for nutritional risk using the Nutritional Risk Screening Scale （NRS 2002）. Patients were divided into study group（ NRS ≥ 3， n=76） and control group（ NRS ＜ 3， n=137）. Serum potassium levels were measured on admission， day 2， day 7， and 1 month. Serum potassium level and the incidence of hypokalemia were compared between the two groups. Results There were 80 cases of hypokalemia （37.56%） in the two groups. The prevalence of hypokalemia in the study group was 47.37%（ 36/76）， which was higher than 32.12%（ 44/137） in the control group（ χ2=4.848，P=0.028）. The average serum potassium level of the study group was lower than that of the control group on admission and day 2 after admission（ P＜0.01）. There was no significant difference in serum potassium level between the two groups on day 7 and 1 month after admission（ P＞ 0.05）. The blood potassium level of the study group was the lowest on day 2（ P＜ 0.05）. Multivariate logistic regression analysis showed that average daily alcohol consumption（ OR=1.657， P=0.041）， duration of alcohol dependence（ OR=1.066， P=0.031） and NRS 2002 score（ OR=1.414， P=0.014） were the risk factors for hypokalemia， while average daily food intake（ OR=0.455，P=0.003） was a protective factor for hypokalemia. Conclusions Alcohol dependent patients are prone to malnutrition and have significantly higher incidence of hypokalemia. Nutritional risk screening and continuous potassium assessment in alcohol-dependent patients deserve attention.