Immune-mediated necrotizing myopathy (IMNM) is a rare autoimmune disease. Its pathogenesis is complex and not clear yet. This article first introduces the important role of immune factors such as autoantigen, specific antibodies, complement and its activation pathways, cytokines, and chemokines. Then, it discusses the influence of non-immune factors such as genetic susceptibility, statin use, endoplasmic reticulum stress, and autophagy on the pathogenesis of IMNM. The aim of this article is to enhance the understanding of the disease mechanism and to provide insights for clinical treatment decisions and drug development.