This study was designed to evaluate the reliability and validity of the Chinese version of the diagnostic and statistical manual (DSM) of mental disorders written by Ely et al as a confusion assessment method for the intensive care unit (CAM-ICU) for diagnosing delirium. Purposive sampling was used to recruit 31 patients in a southern medical center ICU. Data were collected by two interviewers who used CAM-ICU to test inter-rater consistency. DSM served as the delirium diagnosis standard to test CAM-ICU validity and calculate sensitivity and specificity. The inter-rater reliability Kappa value for CAM-ICU applied to delirium diagnosis was .48 (p< .01). The validity PABAK value was .48 (p< .01) and McNemar's test value was p = .72. The sensitivity achieved by the two interviewers was 89%, versus 96% for the doctor. The CAM-ICU is a method that helps ICU nursing staff to detect occurrences of delirium rapidly and easily, permitting early intervention treatment with fewer complications.