Objective To investigate the effect of angiotensin-converting enzyme inhibitor (ACEI) on the cognitive function in patients with chronic heart failure (CHF) and cognitive dysfunction. Methods From September 2017 to February 2019, a total of 60 CHF patients with cognitive dysfunction from Rongjun Hospital of Jiangsu Province and Shanbei Street of Wuxi City was selected and randomized into the treatment group and the control group. The treatment for the control group included etiological treatment, eliminating inducements and improving the symptoms of heart failure. The treatment group were treated with ACEI plus the treatment for the control group. Montreal Cognitive assessment scale (MoCA) was used for the evaluation of cognition, Hamilton anxiety scale (HAMA)for anxiety, and Hamilton depression scale (HAMD)for depression. SPSS statistics 21.0 was used for data analysis. Results Before the intervention, there was no significant difference in MoCA scores and total scores between the two groups (P>0.05). After the intervention, MoCA scores for the treatment group were higher than those for the control group, among which visual space and executive ability [(4.27±0.52) vs(2.70±0.54)] and total score [(24.70±1.09) vs(22.23±1.43)] had significant difference (P<0.01). The scores of MoCA in the treatment group were higher after the intervention than before the intervention, and the total score [(24.70±1.09) vs(22.60±1.54)] and visual space and executive ability [(4.27±0.52) vs(2.77±0.68)] had significant difference (P<0.05). No significant difference was observed between the two groups in the scores for cardiac function, left ventricular ejection fraction, anxiety and depression both before and after the intervention (P>0.05), and no significant difference was observed in the above indices before and after the intervention in two groups (P>0.05). During the treatment period, the cardiac function in the two groups remained stable without induced acute heart failure and adjustment of drug treatment in either the type or the scheme. No serious adverse reactions or new complications occurred in both groups. Conclusion ACEI can improve cognitive function and the ability to perform tasks in CHF patients.