<p>Red-stratum mudstone, as a widely-graded subgrade filling material, can be considered as a special type of soil-rock mixture (SRM). Under the influence of varying rock content, the compaction characteristics and shear behavior of Red-stratum mudstone soil-rock mixture (RM-SRM) exhibit significant complexity. Therefore, this study conducted a series of heavy compaction tests and triaxial shear tests on RM-SRM with different rock content. The effects of rock content, maximum particle size, and moisture content on the maximum dry density of RM-SRM were analyzed. A prediction formula for the maximum dry density of RM-SRM was established, considering the influence of different rock content and maximum particle size, and the validity of this prediction formula was verified through both laboratory and field test data. Furthermore, based on uniform compaction degree, the influence of different rock content on the shear characteristics of RM-SRM was investigated. The effects of different rock content on the stress-strain relationship, mobilized friction angle, and particle breakage index of RM-SRM were clarified. The particle breakage evolution of RM-SRM under different rock content was analyzed based on breakage index.</p>