The development of optical gyro and its application in strapdown inertial system are presented to summarize their tendencies and research directions. The progress of optical gyro technology in America and European and the domestic research state are reviewed after analyzing the operating principle and characteristic of optical gyro，and then the key technology of optical gyro is summarized. The development of strapdown inertial system consisting of optical gyro is presented after introducing the characteristic of strapdown inertial system and the applied trait of optical gyro. The technology adopted by the high precision system research in America is expounded, and then the research tendency of optical gyro strapdown inertial technology is summed up, which can offer references to high accuracy system research and manufacture.