RLG(ring laser gyroscope) was pivotal to the technological revolution transitioning from platform inertial navigation to strapdown inertial navigation in the field of inertial guidance and navigation. To this day, RLG remained the dominant gyroscopic technology in the global high-end inertial sensor market. This article first traced the theoretical origins and feasibility concepts of RLG. Then, it systematically reviewed the development and application history of RLG technology in China and abroad across four stages: initial research, technological breakthroughs, practical advancements, and mass production applications. RLG was invented in the 1960s, with the United States pioneering core key technologies. Building on a dual-track industrial model for commercialization and military-civilian use, its equipment adaptability and high reliability drove a revolutionary advancement in inertial technology from mechanical gyroscopes to optical gyroscopes, achieving widespread application in both civil aviation and military domains. China's RLG research began in the 1970s, gradually overcoming challenges in foundational materials, key technologies, and core processes. It achieved a historic leap from imitation to independent innovation, establishing a complete RLG industrial chain and ultimately achieving full self-reliance. Analysis indicates that RLG is a mature technology with proven performance and reliability, still very robust at the middle and high-end，and is becoming more and more compact as manufacturing advances. Future development priorities for RLG technology will include improving precision through quantum enhancement principal innovation, reducing costs via AI-enabled automated manufacturing, and minimizing size, weight, and power consumption through micro-nano integrated photonic technology.