Abstract： Objective To analyze CT findings of solitary fibrous tumors of the pleura (SFTP) for differentiating benign and malignant lesions.Methods CT findings of 20 benign and 11 malignant SFTPs proved by pathology were retrospectively reviewed. The size,margin,internal structures,blood supplies,invasion to adjacent structures or metastasis and pleural effusion were analyzed and compared between malignant and benign groups.Results The mean diameter of malignant lesions( median diameter:13.5 cm) was larger than that of the benign ( median diameter:7.6 cm,F =6.411,P =0.017 ).Malignant lesions tended to be more heterogeneous (9/11,P =0.002),more invasive to adjacent structures ( 6/11,P =0.001 ) than benign lesions ( 4/20,0/20 ).Serpiginous vessels ( 10/11,P =0.008 ) and pleural effusion (6/11,P =0.038 )were more common in malignant lesions than those in benign lesions (8/20,3/20).Calcification could be found in both benign (2/20) and malignant lesions ( 2/11,P =0.6 ).Furthermore,3D CT angiography could show blood supplies into tumor in 12 lesions (4 benign and 8 malignant SFTPs).Conclusion CT and 3D CTA are helpful in differentiating benign from malignant SFTPs and evaluating the excision of SFTPs.