In this article, first, the technical bottlenecks of ultraviolet lightemitting diodes (UV LEDs) encountered in the current stage of research and development are introduced. Then the inactivation mechanism of UV LEDs to harmful microorganisms in water is analyzed. In the process of microbial inactivation, the different application types of UV LEDs are examined in detail, including the application of UV LEDs in different types of UV reactors, advanced oxidation processes (AOPs) based on UV LEDs, the combined use of UV LEDs with different wavelengths, etc. Finally, the issues of deep UV LEDs in the field of drinking water sterilization and disinfection are summarized and an outlook is put forward.