Abstract: Narrow linewidth lasers play a vital role in cutting-edge fields such as quantum technology, time-frequency transmission, and high-precision sensing due to their extremely low phase noise. Whispering gallery mode optical microcavities, owing to their high quality factor, tiny mode volume, and wide optical transparent window, can significantly enhance the interaction between light and matter. These microcavities not only achieve good laser linewidth narrowing effects across a wide spectral range but also offer excellent tunability, making them a hot topic in narrow linewidth laser research. This paper reviews the research progress of narrow linewidth lasers based on whispering gallery mode microcavities. It first introduces whispering gallery mode microcavities, their thermal noise theoretical foundation, and the principles of laser linewidth evaluation. Then, it discusses the main methods for generating narrow linewidth lasers using whispering gallery mode microcavities, including pumped narrow linewidth lasers based on stimulated Brillouin scattering and stimulated Raman scattering effects, as well as locked narrow linewidth lasers using self-injection locking and Pound-Drever-Hall (PDH) locking technologies. The research status, key technical characteristics, and performance metrics of these methods are summarized. Additionally, the research progress of the National Institute of Metrology in developing narrow linewidth lasers based on high quality factor crystal whispering gallery mode microcavities is introduced. Finally, the paper provides a summary and outlook on the development of narrow linewidth lasers based on whispering gallery mode microcavities.