Background Cognitive impairment and affective symptoms are hallmark features of patients with schizophrenia. This study determines whether a computerized working memory training program improves the patient’s working memory and affective perception. Methods Thirty-nine male patients with schizophrenia, aged 25–65, participated in this study. The study uses a single-blind randomized controlled design. Twenty subjects were assigned to the experimental group and received an eight-week working memory computerized training course comprising four modules of the CogniPlus system. Nineteen subjects were assigned to the control group and received treatment as usual. All subjects received the same assessments twice, including the Mini-Mental Status Examination (MMSE), Working Memory Index (WMI) of Wechsler Adult Intelligence Scale-Third Edition, and the subjective rating of pictures of the International affective picture system by Self-Assessment Manikin (SAM). Results This study shows that computerized working memory training improves WMI and the score for MMSE and produces a significant increase in the pleasure score for S.A.M. for negative pictures, between the pretest and post-test for the experimental group. Conclusions Working memory training improves working memory and emotion perception for patients with chronic schizophrenia and normal cognition. The limitations of this study and suggestions for future study are also discussed.