Synovial hemangioma is a rare benign tumor, yet an important cause of knee symptoms. We reported a 45-year-old male presented with pain and swelling in the left knee joint. Plain radiography showed a small calcification over the suprapatellar region. Sonography of left knee revealed a heterogeneously hypoechoic lesion with increased blood f low and a calcified spot. Computed tomography demonstrated two nodular lesions with moderate degree of contrast enhancement. MRI study showed two nodular lesions with serpentine structure, showing high signal intensity on T2-weighted images. After arthroscopic examination, arthroscopic surgical excision was performed. The pathologic results proved synovial hemangioma.