OBJECTIVE: To explore the possibility and application value of extracranial carotid ultrasound in assessing the progress of MMD. METHODS: We retrospectively analyzed the extracranial carotid ultrasound and DSA data of 89 cases of 53 patients with MMD (moyamoya group) and 90 cases of 45 control patients (control group). According to the DSA data of the moyamoya group, collateral circulation patterns’ grade and Suzuki stage were performed. We analyzed the correlation between collateral circulation patterns and Suzuki stage, and compared the difference of hemodynamic parameters between different grades of collateral circulation patterns. RESULTS: (1) As the Suzuki stage increased, the grade of the collateral circulation pattern subsequently increased. (2) Compared with the control group, the PSV of ICA in the moyamoya group was lower (P<0.01)，but the RI value of CCA and PSV of VA was increased (P<0.05). And the differences in hemodynamic parameters of ECA (including PSV and RI) were not statistically different. (3) Comparing hemodynamic parameters between the different grades of collateral circulation patterns of the control group, Grade 2 showed higher PSV of VA compared with Grade 1 (P <0.05); Grade 3 showed lower RI of ECA compared with Grade 1 and Grade 2 (P < 0.05). CONCLUSION: There is a correlation between collateral circulation patterns and Suzuki stage in adult ischemic MMD. There are differences in the hemodynamic parameters of extracranial carotid ultrasound in different grades of collateral circulation patterns. Extracranial carotid ultrasound can assess the progress of MMD in a timely, effective and convenient manner.