Abstract: Aiming at the case of using rubber particles and soil mixture for foundation backfill, its engineering performance may face the technical difficulties of increased settlement and insufficient bearing capacity. This paper proposes to use cement slurry for improvement. It adopts the resonant column test method to analyze the influence of rubber content, cement content, and peripheral pressure change on the dynamic characteristics of the composite soil body. The results show that rubber content, cement content and effective circumferential pressure are the main factors affecting the decay of normalized shear modulus ratio G/G_max and the growth of damping ratio λ of the mix. An increase in rubber content raises the modulus reduction curve, slowing the attenuation rate of the modulus ratio while simultaneously elevating the damping ratio curve. Higher confining pressure suppresses particle displacement, reducing the modulus ratio decay rate and lifting the modulus ratio curve, but it decreases the damping ratio. Elevated cement content enhances interparticle bonding, increasing the modulus ratio curve and reducing its attenuation rate while lowering the damping ratio curve. Based on the variation pattern of the maximum dynamic shear modulus G_max with rubber content at a fixed cement content of 3.5 g/100 ml, a predictive formula for G_max of cement rubber sand mixtures is derived. Furthermore, recommended parameter values for different working conditions are provided.