Abstract: As a new member of two-dimensional materials, black phosphorus has shown good application prospects in the fields of photoacoustic imaging, photothermal photodynamic therapy, and drug loading due to its excellent characteristics such as good biodegradability, biocompatibility, thickness-dependent tunable direct band-gap, and high surface-to-mass ratio. Because black phosphorus has the characteristics of easy oxidation and degradation, it is coated with relatively stable liposomes or polymeric materials to construct a black phosphorus-based drug delivery system, which shows great potential in tumor treatment and diagnosis and has become a new focus in drug delivery research. In this paper, we introduce the role of black phosphorus in tumor diagnosis and treatment in detail, and summarize the design of black phosphorus-based drug delivery system in recent years as well as its research progress in tumor diagnosis and treatment, in order to provide reference for the research and application of black phosphorus.