Objective To investigate the values of Montreal Cognitive Assessment Scale (MoCA) and Mini-Mental State Examination (MMSE) in detecting Parkinson's disease (PD) with mild cognitive impairment (PDMCI).Methods Random sampling was used to select 75 PDMCI patients, 180 PD patients with normal cognitive function, and 145 healthy controls. These subjects were screened by MoCA and MMSE for PDMCI, and the two scales were compared in terms of sensitivity and specificity.Results In the illiterate group, MMSE had a sensitivity of 93.10% and a specificity of 100%, versus 0% and 92.72% for MoCA. In the primary school group, MMSE had a sensitivity of 87.50% and a specificity of 100%, versus 41.67% and 79.17% for MoCA. In the junior high school and above group, MMSE had a sensitivity of 27.27% and a specificity of 100%, versus 90.91% and 85.71% for MoCA.Conclusions MoCA is suitable for PDMCI detection in people with degrees of junior high school and above, while MMSE for people with degrees below junior high school.