Abstract: Mesoporous silicon nanoparticles are a kind of nanomaterials with special structure and excellent performance, such as large specific surface area, large pore size, good biocompatibility and biodegradability. There are many pores with diameters of 2-50 nm in the surface of these nanoparticles. Mesoporous silicon nanoparticles are used to construct the drug delivery system and improve drug efficacy by loading hydrophobic drugs or anti-tumor drugs, they play a role in bioimaging and photodynamic therapy by loading imaging media for enhanced imaging and treatment effect, and also they are able to be loaded with bone tissue regeneration materials to promote osteogenic differentiation in tissue engineering. This article reviews the biocompatibility of mesoporous silicon nanoparticles and their applications in biomedical fields, such as drug delivery, bioimaging, photodynamic therapy, biosensing, and tissue engineering, and explores the significant potential of mesoporous silicon nanoparticles in scientific research and clinical research.