Objective: To detect the effects of the Rey-Osterrieth complex figure (ROCF) test in the diagnosis of mild to moderate Alzheimer's disease (AD) and mild cognitive impairment (MCI) effect. Methods: Total 117 normal controls, 207 MCI patients, 97 mild-to-moderate AD patients underwent ROCF test and other tests including Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Results: The overall scores of patients in the mild-to-moderate AD and MCI groups were worse than those in the normal control group (P< 0.001). ROCF replication, instant recall, and delayed recall result scores were used to distinguish the AUC value of mild-to-moderate AD from the normal control group (ie, distinguish the accuracy of diagnosis) were 0.882, 0.974, 0.960 (P< 0.001); the AUC values (the accuracy of differential diagnosis) in the identification of MCI and the normal control group were 0.781, 0.745, 0.746 (P< 0.001); the AUC values (accuracy of differential diagnosis) in MCI patients and mild to moderate AD patients were 0.744, 0.843, and 0.816 (P< 0.001). ROCF replication, instant recall, delayed recall and MMSE (r=0.550, r=0.571, r=0.545, P< 0.001), MoCA (r=0.594, r=0.601, r=0.572, P< 0.001), CDR (r = -0.594, r = -0.562, r = -0.539, P< 0.001). There is a good correlation between the scores.Conclusion: The ROCF test has good a accuracy in detecting MCI and mild to moderate AD patients.