Gallium nitride (GaN) is a typical representative of the third generation of semiconductors, which has received wide attention from academia and industry, and is becoming one of the key technologies relied upon to surpass Moore's law in the future. In terms of radio frequency (RF) GaN technology, the two major application-growing industries in telecom and national defense, especially the military sector's increasing demand for advanced radar and communication systems, has driven development of RF GaN devices to higher frequency, higher power and higher reliability. This paper described GaN RF/microwave HEMT, millimeter wave transistor and MMIC (monolithic microwave integrated circuit), the GaN devices space application reliability and radiation hardening and other technical development of the domain. In power electronics, the demand for efficient, green and intelligent energy pulled GaN power electronics, power converters to the directions of fast charging, high efficient and small size. This paper briefly described the commercial and development progress of GaN power devices applied to pure electric and hybrid electric vehicles (EV/HEV), industrial manufacturing, telecommunications infrastructure and other occasions. At the frontier of digital computing, especially quantum computing, GaN is one of the technologies with promising applications, so several highlights of GaN computing and cryogenic electronics research were presented. In summary, this paper gave a general description of the latest trends in several areas of GaN technology development, and sketched out the rough lines of technology development.