【】Objective This study intended to investigate the diagnostic and deficiency of high frequency ultrasound, X-ray and MRI in the diagnosis of psoriatic arthritis ankle lesions.Methods 30 patients with psoriatic arthritis ultrasoound, X-ray and MRI respectively, comparing with the result of the three.Results High frequency ultrasound find 6 cases of synovial thickening,2 cases of bone erosion, 5 cases of articular cavity effusion, 6 cases of tenosynovitis;MRI for synovial thickening of the 3 cases, 2 cases of bone erosion, 6 cases of bone marrow edema, 8 cases of articular cavity effusion.Comparison with high frequency ultrasoundan MRI ,X-ray can only be detected 2 cases of joint bone destruction, lesions show poor outside the joints.High frequency ultrasound and pathological changes of MRI contrast detection number has no statistical significance (P > 0.05).High-frequency ultrasound can detect inflammatory ankle attachment points, x-rays can show the ankle bone lesions, but MRI detects the ankle joint cavity lesions.Conclusions Ultrasound can find psoriatic arthritis ankle lesions outside the cavity lesions, MRI are more advantages for intracavity lesions, compared to X-Ray, the more accurate and comprehensive diagnosis of PsA lesion severity.