Objective To summarize the imaging findings of osteoarthritis (OA) secondary to acetabular dysplasia (AD) in adults, and to analyze the clinical value of different examination methods in the diagnosis of the disease. Methods The imaging data of 300 cases of patients with AD who were admitted in our hospital between January 2013 and October 2015 were collected. All the patients were examined by X-ray. One hundred and twenty-seven patients underwent CT scan and 48 patients underwent MRI examination. All images were transferred to the workstation. According to whether there was secondary OA, they were divided into two groups. The imaging findings were compared between the two groups. The clinical value of different imaging methods in the diagnosis of OA secondary to AD was analyzed. Results In 300 patients with AD, 82 patients (27.33%) were with secondary OA. The CE angle, hip top angle of contingence, acetabular index, coverage of femoral head and space on hip joint of the secondary group were lower than those of non-secondary group (P<0.05). The Sharp angle and inner space of hip joint were higher than those of the non-secondary group (P<0.05). The detection rate of MRI for OA secondary to AD was the highest. Compared with that of CT and X-ray, the differences were significant (P<0.05). Besides, the detection rate of CT was higher than that of X-ray (P<0.05). Conclusion MRI can detect subchondral utricular lesions and articular cartilage degeneration in adults with AD and OA. The detection rate in the diagnosis of adults with AD and surrounding bone cysts is better than that of X-ray and CT.