Abstract: In recent years, more and more attention has been paid to the development of cancer diagnosis and treatment, including nanoparticles-based methods. Silica nanoparticles show great potential in the field of tumor diagnosis and treatment because of its unique physical and chemical properties. The drug delivery system based on SiO₂ NPs can passively or actively target tumor tissues, and controllably release of cytotoxic drug at the tumor tissue by responding to different stimuli modes. It can effectively increase the concentration of anti-tumor drugs at the tumor site and improve treatment efficiency. In addition, SiO₂ NPs can be used for tumor tissue localization and drug tracking by loading contrast agent to achieve the function of biological imaging. In this way, more efficient anti-tumor treatment can be achieved. In this paper, we introduced the preparation methods of SiO₂ NPs and review the research progress of SiO₂ NPs in targeted drug delivery system and biological imaging field.