Background This study aimed to assess the correlation of circulating microRNA-103 (miR-103) and microRNA-107 (miR-107) with disease risk and cognitive impairment of Alzheimer's disease (AD). Methods Plasma samples from 120 AD patients, 120 Parkinson's disease (PD) patients (served as disease control), and 120 healthy controls were collected for miR-103 and miR-107 detections using real-time quantitative polymerase chain reaction. Mini-Mental State Examination (MMSE) score was documented and was used to accordingly assess the dementia severity. Results miR-103 expression was decreased in AD patients compared with PD patients and healthy controls, and receiver operating characteristic (ROC) curve analyses illustrated that it was able to differentiate AD patients from PD patients and healthy controls. Additionally, miR-103 positively correlated with MMSE score and negatively correlated with dementia severity in AD patients. miR-107 expression was lower in AD patients compared with healthy controls but similar between AD patients and PD patients, and ROC curve analyses revealed that it was able to differentiate AD patients from healthy controls but not AD patients from PD patients. miR-107 was positively correlated with MMSE score and negatively correlated with dementia severity in AD patients, while the correlation coefficient of miR-107 with MMSE score was lower than that of miR-103 with MMSE score. Besides, miR-103 was positively correlated with miR-107 in AD patients, PD patients, and healthy controls. Conclusion miR-103 may be a better choice than miR-107 to serve as a potential biomarker for disease risk and disease progression of AD.