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Objective Previous studies have shown that transcranial direct current stimulation(tDCS) led to an improvement of cognitive function in patinets with schizophrenia, but rare study has explored the effect of tDCS on long-term hospitalized chronic schizophrenia with tardive dyskinesia(TD). The present research explored if cognitive function in patients with long-term hospitalized chronic schizophrenia with TD could be improved through tDCS. Methods This study is a randomized, double-blind, sham-controlled clinical trial. Of the 52 patients, 14 dropped out and 38 completed the experiment. Thirty-eight patients on stable treatment regimens were randomly assigned to receive active tDCS(n = 21) or sham stimulation(n = 17) on weekdays of the first, third, and fifth weeks of treatment. Patients performed the Pattern Recognition Memory(PRM) and the Intra/Extradimensional Set Shift (IED) from the Cambridge Neuropsychological Test Automated Battery at baseline, at the 3-week of tDCS treatment (week3), and the end of tDCS treatment (week5). Clinical symptoms were also measured at the baseline and the fifth week using the Scale for the Assessment of Negative Symptoms (SANS) and the Positive and Negative Syndrome Scale (PANSS).Side effects of tDCS were assessed with an experimenter-administered open-ended questionnaire during the whole experiment. Results There were no significant differences in PRM and IED performance metrics, SANS total score and PANSS total score between active and sham tDCS groups at the end of the 5-wk treatment period (all P > 0.05).Furthermore, it was significant difference in the adverse effects of the tingling sensation between the two groups (P < 0.05), but there was no significant difference in other side effects (P > 0.05). Conclusion According to these findings, there is no evidence in support of the use of anodal stimulationover the left dorsolateral prefrontal cortex an approach for improving cognitive function in patients with long-term hospitalized chronic schizophrenia with TD.