Objective To analyze the computed tomography (CT) and magnetic resonance imaging (MRI) findings of extra-adrenal retroperitoneal ganglioneuroma. Methods CT and MRI data of 50 patients with extra-adrenal retroperitoneal ganglioneuroma in The First Affiliated Hospital of Naval Medical University (Second Military Medical University) from Dec. 2011 to Aug. 2021 were retrospectively analyzed and compared with the pathological findings. Among the 50 cases, 31 cases underwent CT plain scan and enhanced scan, 35 cases underwent MRI plain scan and enhanced scan, and 16 cases underwent CT and MRI scan at the same time. Results The tumors in 50 patients were all single and 47 (94%) had clear boundary. The average maximum diameter of the mass was (9.1±3.8) cm. Thirty-two (64%) cases showed pseudopodial and embedded growth along the perivascular space and 18 (36%) cases showed expansive growth. Twenty-one (42%) cases surrounded the abdominal great vessels. Eight (16%) cases showed a little cystic change, 13 (26%) cases were accompanied by spotty calcification, and 6 (12%) cases contained patchy fat. Thirty-one cases showed equal or low density on plain CT images. On MRI T2 weighted images, 30 (86%) cases showed uneven high or slightly high signal. Among the 50 cases, 39 (78%) cases had no obvious or mild enhancement and 11 (22%) cases had moderate or obvious enhancement. All enhancement cases showed progressive delayed enhancement. The enhancement patterns were flake flocculent and line interleaving enhancement in 10 (20%) cases, flake flocculent enhancement in 15 (30%) cases, line interleaving enhancement in 12 (24%) cases, and swirl-like enhancement in 3 (6%) cases. Conclusion Extra-adrenal retroperitoneal ganglioneuroma has certain characteristic imaging manifestations. Preoperative CT and MRI are of great value in diagnosing ganglioneuroma and evaluating the relationship between adjacent large vessels.