Abstract： The purpose of this study was to evaluate the use of serum amyloid A (SAA) detection combined with magnetic resonance spectroscopy (MRS) and diffusion tensor imaging (DTI) in diagnosing cognitive impairment in patients with Parkinson's disease. The study showed that SAA level was significantly higher in the study group than that in the control group, with statistical difference. For diagnostic purpose, the sensitivity, specificity, positive predictive value, negative predictive value and AUC with combined use of SAA, MRS and DTI were significantly higher than those with SAA, MRS or DTI used alone, with statistical difference. In summary, SAA detection combined with MRS and DTI can significantly improve the sensitivity and specificity in identifying cognitive impairment in patients with Parkinson’s disease, showing a diagnostic performance.