Objective: To describe the MRI findings and discuss the pathogenesis formation mechanism of syringomyelia in the patients after spine surgical operation. Methods: Totally 13 patients were been enrolled in the study. Before operation, none of our patients presented with spinal cord syringomyelia. The mean follow-up duration was 6 years (range 2-10 months) by MRI. Four of the 13 patients after spinal cord tumor removed operation, 3 patients after spinal trauma operation, 2 cases had scoliosis before, 2 cases were cervical spondylotic myelopathy and 2 cases had tethered cord syndrome before operation. MR features of pre- and post-operation on all patients were been studied in contrast with surgical results and clinical symptoms. The radiology diagnostic was made by 3 different radiologists respectively. The characteristics of length, width, signals, shape of cavity and spinal cord position as well as subarachnoid shape were focused on. Results: All the patients had no syringomyelia on MRI before operation. The spinal cord of 7 patients showed persist compression and 2 patients had tethered cord before operation. MRI features of syringomyelia after operation in our cases showed longitudinal cavity with syrinx fluid had T1 and T2 relation characteristics of cerebrospinal fluid (CSF). The mean length was 5.5 spinal segment, 4 cord of 13 patients presented cord compressed from anterior materials, 4 occurred postoperative adhesion to the back of lumbar spinal canal and spinal cord of 1 cases clung to the front wall of cervical spinal canal. Conclusion: The mechanism of syringomyelia in the patients after spinal surgical intervention may be the persisting compression or intention of the spinal cord in the period of pre- or post-operation. The edema, cyst, malacia of spinal cord are the most important lesions and risk factors resulted in the syringomyelia.