To quantitatively characterize the visuo-oculomotor and vestibulo-oculomotor pathways in progressive supranuclear palsy (PSP) and Parkinson's disease (PD) using video-oculography (VOG), delineate the profile of oculomotor dysfunction in each disorder, and identify parameters with differential diagnostic value. Methods: We retrospectively analyzed vestibulo-ocular reflex suppression (VOG) data from 24 PSP patients and 48 PD patients. The data included measurements of spontaneous nystagmus, gaze holding, saccades, head-shaking test, and the vestibulo-ocular reflex suppression (VORS) test. Results: In PSP patients, the incidence of restricted vertical gaze range, decreased vertical saccadic peak velocity, saccadic hypometria and prolonged latency, horizontal gaze-evoked nystagmus (GEN), horizontal saccade hypometria and reduced velocity, as well as VORS functional abnormalities, were all significantly higher than those in PD patients (P< 0.05 for all). Spontaneous nystagmus was significantly more prevalent in PD patients than that in PSP patients (P= 0.006). The incidence of saccadic intrusions, vertical saccade hypometria, prolonged horizontal saccade latency, and perverted head-shaking nystagmus (pHSN) showed no significant difference between the PSP and PD groups (P>0.05 for all). Conclusion: Oculomotor and vestibulo-ocular assessments holds significant clinical value in differentiating PSP from PD. Specifically, vertical saccade dysfunction and VORS abnormalities serve as critical differential diagnosis indicators for distinguishing between the two conditions.