Objective To investigate the changes of diameter of the main trunk of the extracranial segment of the facial nerve， local hemodynamics and facial muscle thickness in patients with peripheral facial palsy （PFP） at acute stage by high frequency ultrasound（HFUS）. Methods Sixty patients with acute PFP were enrolled as the PFP group， and 30 healthy people were selected as the control group.The following facial parameters were scanned and recorded using HFUS： diameter of the main trunk of the extracranial segment of the facial nerve （FN-d）， facial artery diameter （FA-d）， facial artery systolic velocity （FA-Vs）， facial artery diastolic velocity （FA-Vd）， facial artery resistance index （FA-RI）， frontalis muscle thickness （FM-t）， depressor anguli oris muscle thickness （DAO-t）， and depressor labii inferioris muscle thickness （DLI-t）.The feasibility of facial parameters in the diagnosis of acute-phase peripheral facial palsy （PFP） was evaluated， with intra-group and inter-group variability comparisons performed. Pearson correlation analysis was conducted to evaluate the relationship between acute-phase facial parameters and House-Brackmann （H-B） scale scores in PFP patients. Results （1）The H-B score of the PFP group was significantly lower than that of the control group， and the difference was statistically significant （P < 0.05）. （2）The reliability of repeated measurements of facial parameters by different testers is good （ICC > 0.75）. （3）The FN-d and FA-RI values on the affected side of PFP group were higher than those on the healthy side and control group， and FA-Vs， FA-Vd， DAO-t and DLI-t values were lower than those on the healthy side and control group， with statistical significance （P < 0.05）. （4）The FN-d and FA-RI values of the affected side in the PFP group were negatively correlated with the H-S scale score （r = -0.847， P < 0.05； r = -0.863， P < 0.05）； FA Vs， FA Vd， DAO-t， DLI-t are positively correlated with H-S scale scores （r = 0.808， P < 0.05； r = 0.757， P < 0.05； r = 0.836， P < 0.05； r = 0.694， P < 0.05）. Conclusions HFUS can effectively detect the characteristic changes such as the increase in the diameter of the extrcranial facial nerve trunk， local microcirculation disturbance and facial muscle atrophy in patients with PFP in the acute stage， and the increase and decrease of FN-d， FA Vs， FA Vd， FA-RI， DAO-t， and DLI-t can accurately reflect the improvement or progress of PFP， which has important guiding significance for clinical disease monitoring and efficacy evaluation.