Objective To explore the influence of nutrition status on cognitive function in patients with Alzheimer disease(AD)so as to provide theoretical support for clinical intervention. Methods A total of 182 patients with AD(over 60 years old)treated in Neurology Departments and Geriatrics Department from three class Ⅲ grade A general hospitals in Taiyuan City were selected as study subjects by purposive sampling from June to December 2016. The cognitive function and nutrition status were evaluated with the mini-mental state examination(MMSE)and the short-form mini-nutritional assessment(MNA-SF)respectively. The relation between them was analyzed with variance analysis,correlation analysis and regression analysis. Results The average score of MMSE and the total score of MNA-SF were(18.13±5.44)and(9.66±2.40). There were statistically significant differences in the dimension scores(weight loss during the last 3 months, having suffered psychological stress or acute disease in the past 3 months,mobility,neuropsychological problems,having food intake declined over the past 3 months due to loss of appetite,digestive problem, chewing or swallowing difficulties)and the total score of nutrition status among groups of mild,moderate and severe cognitive impairment(F=4.600,5.046,12.265,12.962,64.361,12.767;P<0.05). Pearson correlation analysis showed that the dimension scores(weight loss during the last 3 months,mobility,neuropsychological problems,having food intake declined over the past 3 months due to loss of appetite,digestive problem,chewing or swallowing difficulties)and the total score of nutrition status had positive correlations with the score of MMSE with significant differences(r=0.033,0.510,0.324,0.550,0.386;P<0.05). The score of dimension on having suffered psychological stress or acute disease in the past 3 months had a significantly negative correlation with the score of MMSE(r=-0.166,P<0.05). Regression analysis revealed that there was still a positive correlation between the total score of nutrition status and the score of MMSE after adjusting ages,days for reading books and newspapers one week,being with brain diseases or medical histories(β′=0.365,P<0.05). Conclusions Medical staff should strengthen evaluation on early nutrition status in AD patients and take effective interventions so as to delay the progression of cognitive impairment and improve the quality of life of patients.