In order to establish a calculation method for surrounding rock deformation pressure applicable to deep-buried four-track high-speed railway tunnels, the staged construction process is equivalently divided into six phases based on Protodyakonov’s theory and arching theory, and the lateral and longitudinal arching mechanisms in each phase were analyzed. Considering the bearing characteristics of such tunnels, a dimensionless parameter—the deformation pressure coefficient was proposed, and an equivalent calculation method incorporating the evolution of construction-induced loads was developed. The correctness of the proposed theory was validated using monitoring data from the first batch of deep-buried four-track high-speed railway tunnels in China. The results show that the main load borne by these tunnels is deformation pressure, and that existing calculation methods fail to accurately reflect the actual stress state. In Class III, IV, and V surrounding rocks, the theoretical loads derived from the proposed method are approximately 62.73%, 39.43%, and 26.60% of those calculated using the Protodyakonov’s theory, and about 84.14%~91.45%, 53.68%~61.73%, and 36.24%~42.63% of those calculated according to code for design of railway tunnels, respectively. These results more accurately reflect the actual bearing conditions of deep-buried four-track high-speed railway (HSR) tunnels. When Protodyakonov’s theory to is adopted to estimate the surrounding rock loads of such tunnels, the deformation pressure coefficient can be taken as 0.63, 0.37, and 0.27 for Class III, IV, and V rocks, respectively. When the code for design of railway tunnels is used, the deformation pressure coefficient of 0.84~0.91, 0.54~0.62, and 0.36~0.43 are recommended. These findings provide theoretical support for updating the load concept and improving the structural design methodology of deep-buried four-track HSR tunnels.