<p>The rock mass compressive strength is one of the key parameters for the design and construction of open-pit and underground rock engineering in metal mines. Obtaining accurate rock mass compressive strength is crucial for in-depth analysis of the deformation and failure behavior of surrounding rock in rock engineering. In this study, the commonly used empirical equations for estimating the compressive strength and deformation modulus of rock masses were reviewed. Based on laboratory tests and field investigations, these empirical equations were compared and analyzed, and the optimal empirical equation was determined. Additionally, the linear correlation between the uniaxial compressive strength of intact hard rock and the damage stress was summarized, as well as that between the damage stress and the elastic modulus, and that between the rock mass compressive strength, damage stress, and deformation modulus. The relationship between the intact hard rock critical strain and damage stress, as well as rock mass critical strain and intact hard rock critical strain, was established based on the expression of intact hard rock critical strain and rock mass critical strain. The analysis of the critical strain of intact hard rock shows that the critical strain values of the rock mass are lower than those of the corresponding rocks. The results show that the estimation equation of the rock mass compressive strength based on critical strain theory exhibits good consistency with the results estimated by traditional Aydan and Dalgic empirical methods, with a correlation coefficient of 0.9455. This study provides a new theory and analytical tool for calculating the rock mass compressive strength in open-pit and underground engineering in metal mines, thereby ensuring the safety and economy of rock engineering to a greater extent.</p>