Information is the reflection of the attributes of objective things and people’s thoughts, and information acquisition ability and information processing level are the vital symbols of the process of human society. In recent years, with the rapid development of the new generation digital technology, information processing has entered the Big Machine Era, the information system of which greatly promotes the development of the economy and society, drives profound changes in various trades and industries, and changes people’s lives. The wide application of digital technology in the power industry has facilitated the transformation of the power system from the physical system, cyber-physical system to the social-cyber-physical system. In this paper, the development course of information technology is reviewed and the evolution process of power system digitalization is systematically expounded. The development trend of digitization in three dimensions, including the physical world, information space and society, is analyzed. In the end, the digitization technology of power system is prospected.