The rotating detonation combustor is a promising approach to consume the incompletely burned gases laden with solid particles that are produced by solid propellants. The present study numerically investigates the propagation characteristics of the pyrolysis gas rotating detonation laden with solid particles. The parametric effects of solid particles on the detonation are analyzed, including the particle type, size, and mass loading ratio. Results show that particles tend to concentrate behind the contact surface-slip line under the effect of the velocity shear layer. Then, the low-temperature region forms due to the substantial heat absorption. The massive exchange of momentum and energy between particles and the gas phase in these regions also promotes the occurrence of the Kelvin–Helmholtz instability, leading to the disruption of the velocity shear layer. With the increase in particle mass loading ratio, the detonation propagation speed decreases, and the two variables are almost linearly related. For the combustible carbon particles case with a mass loading ratio of 10.0%, the excessive temperature drops near the triple point leads to intermittent local quenching, which further reduces the propagation speed. An increase in particle diameter leads to a rise in the detonation propagation speed due to higher heat absorption and momentum absorption, and the speed roughly decreases linearly with the reciprocal of the particle diameter. In the study, when the particle diameter is large enough (dp≥5 μm or St>1), the influence of particles on the flow field is nearly negligible.