Among the allotropes of phosphorus, black phosphorus (BP) is one of the most thermodynamically stable structures. Due to its unique physical and chemical properties, BP has shown considerable potential in many applications, such as field-effect transistors, energy storage and conversion, and photocatalysis. However, low-dimensional BP is easily corroded by oxygen and water owing to the large specific surface area and unbonded lone pair electrons on the surface, which reduces its chemical stability in the environment. As a result, different passivation approaches, relying on noncovalent bonding, covalent functionalization, and surface coordination, are employed to enhance the stability and performance of BP. In this review, the degradation mechanisms of BP are first analyzed for the material in both its ground state and excited state. Subsequently, the promising strategies for improving stability are overviewed. A comprehensive and in-depth understanding of the oxidation mechanisms and protection strategies of BP will provide guidance for the large-scale applications of BP and its derivatives.