The continuous increase of peak-to-average power ratio (PAPR) makes the wireless communication terminals require power amplifiers with higher power, efficiency, and frequency. The existing analog power amplifier was the last barrier for the fully digital base station, of which efficiency and output power were insufficient to meet the needs. With the merits of high output power, speed and efficiency, GaN digital power amplifier operating at switching mode, was one of the keys to realize digital base station. The GaN digital power amplifier could still operate at a higher efficiency even for the input with high PAPR to make up for the lack of efficiency of analog power amplifier at the same situation. This paper outlined the working principle of the GaN digital power amplifier, summarized recent technological advances and challenges at home and abroad, and described the future development and optimization of the GaN digital power amplifier.