Objective To compare the application of CT and MRI in the diagnosis of jmeniscus injury of knee jointoint meniscus injury. Methods The clinical data of 41 cases of patients with suspected meniscus injury of knee joint were analyzed retrospectively. Both of CT and MRI diagnosis were performed. The diagnostic results and imaging findings were compared and were with arthroscopy. Results Arthroscopy was taken as the golden standard and the accuracy, sensitivity and specificity of MRI in diagnosis of meniscus injury were 97.56%, 97.01% and 100%, respectively which were significantly higher than those of CT (79.27%, 82.09%, 66.67%). CT showed that the shape of meniscus changed, and was obviously enlarged and the edge was rough. There was low density shadow in meniscus; Tear meniscus shifted. There were liquid aggregation of joint cavity and multiple bubble inflation signs in some parts. On T2, MRI of grade I injury showed high signal shadow in the meniscus. Grade Ⅱinjury showed horizontal and vertical high signal shadow on T2. Grade Ⅲ showed high signal shadow on T2 and extends to the edge of the articular surface. Conclusion The accuracy rate of MRI in the diagnosis of meniscus injury of knee joint is higher than that of CT, and it can show the location and changes of shape of the meniscus.