In the era of Industry 4.0, digital transformation has become a strategic highland for enterprises all over the world. Due to the macrocosm and complexity of digital transformation, the digital maturity model, as a tool to describe and guide enterprises to formulate digital transformation strategies, has become a hot spot in the current industry and academia. Firstly, by combing the relevant literature on the digital maturity model of Industry 4.0, this paper applies descriptive statistical analysis to summarize the basic situation of the models developed by industry and academia. Secondly, this paper systematically summarizes the concept definition, model features, and element principles of the digital maturity model, shedding light on what the digital maturity model is. Thirdly, this paper systematically sorts out the new expansions of the application field, the new approaches to evaluation and measurement, the new levels of maturity system, and the problems in the application process of the digital maturity model. Finally, this paper constructs the development and research framework of the digital maturity model of Industry 4.0 based on the three-tier perspective of “point-line-surface”, and discusses future research directions. The main contributions of this paper are that: It clarifies the development and research context of the digital maturity model of Industry 4.0, systematically explains the key elements of the model, provides directional guidance for deepening the development and research of the model, and further provides conceptual cognition for the crucial elements and links related to the enterprise practice of digital transformation.