Photonic crystal surface-emitting laser (PCSEL) is a new type of semiconductor laser, which can produce high-power laser emission with ultralow divergence (less than 1°). It has an important application prospect in light detection and ranging equipment, space communication, sensing and material processing. It can be divided into two types: defect mode and band-edge mode. The band-edge mode PCSEL has the following advantages: it has single-mode and easy two-dimensional integration. Therefore, the basic principle and research progress of band-edge mode of a PCSEL are briefly introduced in this study. Based on the theoretical derivation and several reported examples, how to improve the output power of a band-edge mode PCSEL is discussed and a new method of power enhancement is proposed. Finally, the development trend of a band-edge mode PCSEL is prospected.