<p>This study aims to utilize Color Doppler Ultrasound to collect blood flow parameters of the medial circumflex femoral artery and explore the changes in blood flow in osteonecrosis of the femoral head, providing objective indicators for clinical assessment and prognosis. Color Doppler Ultrasound was used to examine the medial circumflex femoral artery in 30 patients with osteonecrosis of the femoral head (52 hips: ARCO Stage I—2 hips, Stage II—24 hips, Stage III—24 hips, Stage IV—2 hips) and 30 healthy controls (57 hips). Arterial diameter and blood flow parameters [peak systolic velocity, resistance index, pulsatility index] were collected and analyzed for vascular and blood flow characteristics in osteonecrosis of the femoral head. (1) Compared with the healthy group, the osteonecrosis group showed significantly lower peak systolic velocity and resistance index, while no significant differences were observed in arterial diameter and pulsatility index. (2) Arterial diameter in Stage I was significantly larger than in Stages II, III, and IV, with no significant differences observed among Stages II, III, and IV. Peak systolic velocity, resistance index, and pulsatility index all significantly decreased with disease progression from Stage I to Stage IV, but no significant difference in pulsatility index was found between Stages II and III. (3) There was no significant difference in arterial diameter between the non-collapsed and collapsed groups; however, peak systolic velocity, resistance index, and pulsatility index were all significantly lower in the collapsed group compared to the non-collapsed group. (1) The alterations in blood supply in femoral head necrosis primarily manifest as changes in blood flow parameters. (2) Vascular morphology and blood flow parameters could potentially be useful indicators for assessing the progression of femoral head necrosis. (3) Changes in blood flow parameters may provide valuable insights into the risk of femoral head collapse.</p>