The aim of the present study was to analyze the long-term effects of transcranial direct current stimulation (tDCS) of the bilateral prefrontal cortex combined with computer-assisted cognitive training on working memory and cognitive function in healthy older adults aged at least 65 years. Forty healthy older adults were enrolled and randomly assigned to two groups: anodal and sham tDCS. All participants completed 10 sessions of computer-assisted cognitive training, combined with tDCS of the bilateral prefrontal cortex. The accuracy of the verbal working memory task and performance of the digit span forward test were significantly improved after computer-assisted cognitive training combined with bifrontal anodal tDCS as compared with that after computer-assisted cognitive training combined with sham tDCS. Moreover, the effect lasts for 4 weeks in the verbal working memory task. We suggest that the tDCS-induced changes in the bilateral prefrontal excitability during computer-assisted cognitive training may have beneficial effects on age-related cognitive decrement in healthy older adults.