Coronavirus disease 2019 (COVID-19) has been classified as a pandemic, and mental hospitals located in epidemic centers have been affected. Social isolation is an important and irreplaceable measure to control the spread of the epidemic. In this study, schizophrenic patients who were subjected to social isolation after close contact with COVID-19 patients were used as participants to explore the impact of social isolation on common inflammatory indicators and psychological characteristics. A total of 30 patients with schizophrenia were recruited from Wuhan Mental Health Center. In addition, 30 ordinary schizophrenic patients were matched with the isolation group and were recruited from another branch of Wuhan Mental Health Center as controls. We compared the differences in common inflammatory indicators and psychological characteristics between the isolated group and the control group, and longitudinal comparison of the differences in the above indicators before and after isolation among the isolation group. The Chinese Perceived Stress Scale (CPSS) score, Hamilton Depression Scale (HAMD) score and Hamilton Anxiety Scale (HAMA) score of the isolation group were significantly higher than those of the control group (p = 0.00, 0.00, 0.00, respectively). The C-reactive protein (CRP) level, CPSS score, HAMA score and Pittsburgh sleep quality index (PSQI) score of the isolation group were significantly higher after isolation (p = 0.01, 0.00, 0.00, 0.00, 0.00, respectively). Inpatients of schizophrenia suffered from social isolation due to COVID-19 have a severe psychological burden. Social isolation caused patients to develop a weak inflammatory state and led to worse anxiety and sleep quality.