Abstract: The observability of underground engineering, such as coal mining, is extremely limited, which makes it difficult to obtain reliable pre-analysis basis for many complex engineering problems. Especially in face of new engineering environment brought about by deep conditions and high-intensity mining, the applicability of the existing theoretical system and technical solutions is facing severe challenges. Based on the technical characteristics of the digital era, a digital rock mechanics solution that integrates data laws, mechanical logic and engineering experience is proposed. The solution makes full use of the objective characteristics of real engineering laws contained in engineering data, and gives a specific mode of underlying integration among theoretical achievements, engineering experience and data law mining. Through the non-damaged inference of mechanical parameters of coal specimens, the feasibility of the above technical path is verified, and the data mining and utilization with both reliability and interpretability are realized. Furthermore, a digital rock mechanics theoretical system with rock physical properties, geological structure and spatial stress as the basic elements is established, and a general operation mode of digital rock mechanics underground engineering with the steps of “engineering sketch, physical knowledge embedding, professional knowledge integration, decision generation” is proposed. The reliability of the digital rock mechanics solution is verified by the application in complex engineering, which provides a practical implementation path for the digital transformation and intelligent upgrading of underground engineering such as coal mining.