Abstract Objectives This study aims to explore the reliability, validity, and feasibility of Clinically Useful Depression Outcome Scale (CUDOS) in screening mixed features in patients diagnosed with mania. Methods A total of 109 patients with (hypo‐) manic episode were recruited. The reliability of Chinese version of CUDOS (CUDOS‐C) were analyzed with Cronbach's alpha and intraclass correlation coefficient (ICC). Spearman correlation coefficient was used to analyze the validity by comparing the correlation between CUDOS‐C and Patient Health Questionnaire‐9 (PHQ‐9), 32‐item Hypomania Checklist (HCL‐32). The score of MINI (hypo‐) manic episode with mixed features—DSM‐5 Module—Chinese version(MINI‐M‐C) ≥ 2 was considered as the gold standard of mixed features, and the receiver operating characteristic (ROC) curve analysis was used to calculate the optimal cut‐off values of CUDOS‐C score. Results The Cronbach's alpha value of CUDOS‐C was 0.898, and the ICC of CUDOS‐C test‐retest was 0.880 (95% CI: 0.812‐0.923, p