Since the discovery of graphene,two-dimensional (2D) semiconductors have been attracted intensive in-terest due to their unique properties.They have exhibited potential applications in next generation elec-tronic and optoelectronic devices.However,most of the 2D semiconductor are known to suffer from the ambient oxidation which degrade the materials and therefore hinder us from the intrinsic materials\' properties and the optimized performance of devices.In this review,we summarize the recent progress on both fundamentals and applications of the oxidations of 2D semiconductors.We begin with the oxida-tion mechanisms in black phosphorus,transition metal dichalcogenides and transition metal monochalco-genides considering the factors such as oxygen,water,and light.Then we show the commonly employed passivation techniques.In the end,the emerging applications utilizing controlled oxidations will be in-troduced.