Objective To explore the effect of cognitive training synchronized with transcranial direct current stimulation （tDCS） for the treatment of working memory in patients with post-stroke cognitive impairment （PSCI）. Methods From December 2022 to July 2023， 60 patients with PSCI admitted to the Rehabilitation Department of Xuzhou Central Hospital and Xuzhou Rehabilitation Hospital were selected as the research subject. Using the random number table method， patients were randomly divided into the pseudo stimulation group， experimental group A， and experimental group B， with 20 cases in each group. All three groups received conventional medication and rehabilitation training， on which the pseudo stimulation group received both cognitive training and tDCS pseudo stimulation therapy； experimental group A received both cognitive training and tDCS therapy； experimental group B received tDCS therapy 2 h after the end of cognitive training. Both cognitive training and tDCS treatment were 5 times per week for 4 weeks. Before and after treatment， the Montreal Cognitive Assessment （MoCA）， Digital Span Test （DST）， n-back task （including 0-back， 1-back）， Modified Barthel Index （MBI）， and quantitative electroencephalogram ［including delta theta/alpha beta ratio （DTABR）， alpha relative power （αRP）， and θ relative power （θRP）］ were used to compare the cognitive function， working memory storage and information encoding ability， digital working memory， activity of daily living， and cranial nerve function of the three groups of patients. Results There was no statistically significant difference in MoCA scores， DST scores， 0-back scores， 1-back scores， MBI scores， DTABR， αRP and θRP among the three groups of patients before treatment （all P ＞ 0.05）. The difference in MoCA， DST， 0-back， 1-back， and MBI scores and the difference in DTABR， αRP， and θRP before and after treatment of the 3 groups were statistically significant （all P＜ 0.05）. The difference in MoCA， DST， 0-back， 1-back， and MBI scores and the difference in DTABR， αRP， and θRP before and after treatment in the experimental groups A and B were higher than those in the pseudo stimulation group， and the differences were statistically significant （all P ＜ 0.05）. The difference in MoCA， DST， 1-back score and the difference in DTABR， θRP before and after treatment in the experimental group A were higher than that in experimental group B， and the difference were statistically significant （all P＜ 0.05）. Conclusions Cognitive training and synchronized tDCS have more advantages in improving the working memory of patients with PSCI compared to separate treatment.