Objective: To study the changes and clinical significance of ultrasonic detection of quadriceps femoris and femoral artery hemodynamics in patients with distal limb fracture. Methods: Fifty-three patients with distal lower extremity fractures in Sichuan Provincial Orthopaedic Hospital from April 2019 to June 2020 were selected for the study. The quadriceps femoris (cross-sectional area of rectus femoris, thickness of medial femoris, thickness of lateral femoris, thickness of medial femoris, thickness of rectus femoris), femoral artery hemodynamics (femoral artery end diastolic velocity, mean blood flow velocity, pulsatility index, early diastolic reverse blood flow velocity and reverse blood flow duration, peak systolic velocity) were measured by color Doppler ultrasound diagnostic instrument on the 1st and 14th day after admission. Results: On the 14th day of admission, the cross-sectional area of rectus femoris, the thickness of medial femoris, lateral femoris, medial femoris and rectus femoris of the healthy side and the affected side were significantly decreased compared with the first day of admission, and the difference was statistically significant (P<0.05). On the 14th day of admission, the end diastolic velocity and average blood flow velocity of the healthy side and the affected side were significantly higher than those on the 1st day of admission, while the pulsatility index, early diastolic reverse blood flow velocity and reverse blood flow duration were significantly lower than those on the 1st day of admission, and the difference was statistically significant (P<0.05), there was no significant difference in the peak systolic velocity between the healthy side and the affected side compared with the first day after admission (P>0.05). Conclusion: Patients with distal limb fracture are very likely to develop disuse muscular atrophy due to the immobilization by lying in bed with the main features of ultrasound in the reduction of cross-sectional area and thickness of quadriceps femoris and change of blood flow parameters of femoral artery in diastolic period.