The rock uniaxial compressive strength (UCS) is the basic parameter for support designs in underground engineering. In particular, the rock UCS should be obtained rapidly for underground engineering with complex geological conditions, such as soft rock, fracture areas, and high stress, to adjust the excavation and support plan and ensure construction safety. To solve the problem of obtaining real-time rock UCS at engineering sites, a rock UCS forecast idea is proposed using digital core drilling. The digital core drilling tests and uniaxial compression tests are performed based on the developed rock mass digital drilling system. The results indicate that the drilling parameters are highly responsive to the rock UCS. Based on the cutting and fracture characteristics of the rock digital core drilling, the mechanical analysis of rock cutting provides the digital core drilling strength, and a quantitative relationship model (CDP-UCS model) for the digital core drilling parameters and rock UCS is established. Thus, the digital core drilling-based rock UCS forecast method is proposed to provide a theoretical basis for continuous and quick testing of the surrounding rock UCS.