Abstract: Objective:To explore the guideline effects of MRI with low electric field intensity on operation of knee joints.Methods:The MRI results of 63 cases with injury knee verified through operation or arthroscopes pathology were retrospectively analyzed.Results:In 48 cases with meniscus injury,MRI showed that there were abnormal linar,strip and star shape hyperintense in meniscus.In 21 cases with anterior cruciate ligaments injury,8 cases with the posterior cruciate ligament injury and 9 cases with collateral ligaments injury,MRI showed that the ligaments continuity were injury and tearing and abnormal linar and strip sign existed inside of ligament.In 49 cases with knee joint effusion,MRI showed that high T2 weighted images(T2WI) and low T1 weighted images signal appeared in cavity of joints.In 19 cases with hiding bone fracture,the linar and strip high T2WI signal of MRI were detected in sclerotin.Conclusions:The results of MRI with low electric intensity for injured knee joints have guideline value for clinical operation.