The imagings have always been an important means of diagnosing and assessing sacroiliitis. Magnetic resonance imaging (MRI) has the advantages of early detection to evaluate sacroiliitis in the diagnosis of diseases related to sacroiliitis and has an important role in clinical Decisionmaking. There are many diseases related to sacroiliitis in the clinic, such as spondyloarthritis, joint degenerative, joint infections, and tumors. In clinic those misdiagnosis causes are mostly caused by misreading of the imagings, and misdiagnosis may cause great loss to the patient's spirit and economy. This article summarizes the MRI features of the sacroiliac and clinical in spondyloarthritis and related differential diagnosis. In our clinical works, sacroiliitis suggested in imagings may be involved in rheumatology and immunology, hematology, endocrinology, infectious diseases,and tumors and so on. For some difficult cases, clinicians should combine the age, history, symptoms, signs, laboratory tests, and imaging examinations to analyze and judge it in a comprehensive manner to avoid misdiagnosis. Therefore, this article reviews the MRI findings of sacroiliitis caused by different diseases.