Abstract: Objective To investigate the characteristics and clinical significance of ultrasonography in haemophilic A arthropathy of knee and ankle joints. Methods The knee (n=55) and ankle joints (n=55) of 28 patients with the diagnosis of haemophilic A in our hospital from January, 2015 to June, 2016 were evaluated with ultrasonography and scored according to MELCHIORRE ultrasound score. The correlations between ultrasound score synovial hypertrophy, knee joints and cartilage damage, ankle joints were analyzed respectively. Results There were 28 male patients with median age33. 4 (6-69) years old enrolled in this study. The average ultrasound score of knee and ankle joints were 5. 16 ±0. 67 and 3. 87 ±0. 57 respectively, which had significant statistically (P < 0. 01), and the incidence of bone erosion of knee and ankle joints had statistical significance (P < 0. 05). The significant difference of ultrasound score was found between mild and moderate, severe haemophilia A (P < 0. 01), but had no statistical significance between moderate and severe haemophilia A (P=0. 134). The ultrasound score according to age < 18 and ≥ 18 years old groups were 3. 50 ±1. 00, 4. 87 ±0. 482 respectively, which had no statistical significance (P=0. 169). A positive correlation between knee and ankle joints of ultrasound score was demonstrated (r=0. 479, P < 0. 01); a significant positive correlation between synovial hypertrophy and cartilage damage of ultrasound score was demonstrated (r=0. 728, P < 0. 01). Conclusion Ultrasound can effectively identify haemophilia A joint lesions of knee and ankle joints, which was a fast, effective, safe and available inspection method in the assessment of haemophilia A arthropathy of knee and ankle joints and had remarkable clinical practical value.