The coal-rock mass surrounding roadways constitutes a typical “loading-bearing” binary integrated structure, making it worthwhile to explore stiffness theory from the perspective of the coal-rock “loading-bearing” system. Existing classification methods for rockburst were analyzed in this study, and they were combined with stiffness theory to elucidate the occurrence process of rockburst. The theoretical boundary of coal-rock bearing structures was defined, and the concept of dynamic stiffness was introduced to analyze the occurrence process of dynamic-static combined rockbursts. Furthermore, the strength-stiffness theory for rockburst in roadways was extended,which was validated through uniaxial compression experiments on four rock types—fine sandstone, red sandstone, mudstone, and coal—as well as three types of coal-rock combinations formed through their integration. The result indicates that a rockburst occurs when the ultimate strength of the bearing system is less than the load exerted by the loading system (strength condition), and when the absolute value of post-peak stiffness of the bearing system exceeds the stiffness of the loading system, which in turn exceeds the pre-peak stiffness of the bearing system (stiffness condition). Cosine similarity, gray distribution probability, and particle information (quantity, area, length) extracted from images were employed to quantitatively analyze the subject and degree of damage during mechanical testing. Additionally, the experimental results were refined into four typical load-deformation curve mechanical models, effectively demonstrating the stress and stiffness conditions of the strength-stiffness theory from energy perspectives. Finally, existing anti-impact measures were synthesized based on the strength-stiffness theory, providing new insights for analyzing anti-impact mechanisms.