Objectives To explore the impact of case management on the cognitive function of patients with severe mental disorders. Methods A total of 240 patients were recruited from Chongqing from November 2017 to January 2018. Patients were divided into a routine follow-up control group（ n=115） and a case management group（ n=125） using a single-group consent to Zelen's randomized controlled trial. The control group was followed up according to the requirements of the management criteria for severe mental disorders. The case management group went through a variety of cognitive rehabilitation activities. The revised Wechsler Adult Intelligence Scale subscales-Digital Width and Symbol Subscale， Language Fluency Test， Connection Test- Awere used to evaluate all the patients at the pre-intervention and 3 months， 6 months， and 12 months after the intervention time marks. Results The results of repeated measurement variance analysis showed that there were significant differences between the two groups in the scores of Digital Width and Symbol Subscale， Language Fluency Test， Completion Time and Error Number of Connection Test A（ F=11.115，6.918，6.128，21.523，4.457， 5.693，P＜0.01）. The time main effect（ F=141.064，158.939，468.552，419.484，70.981，104.701， P＜0.01）， and interaction（ F=167.652，168.388，384.422，235.782，53.549，19.324， P ＜ 0.01） were both statistically significant. Conclusions Case management can improve the cognitive function of patients with severe mental disorders.