Composite particles composed of solid powders and a polymer were prepared by semi-chemical recycle of wasted plastics. Wasted expanded polystyrene was used as a raw material. Also, both of magnetite and silicon carbide powders were used as solid powders. In the experiment, the oil phase dissolving expanded polystyrene was dispersed as much fine droplets in the continuous water phase. Two kinds of powders were added at the same time or separately in the O/W dispersion. The mean diameter of composite particles was strongly affected by the addition time when silicon carbide powder was added into the dispersion. Composite particles were found to have the structure that a polymer particle was covered with solid powders. Furthermore, it was found that the gradient adhesion layer due to two solid powders was able to be formed on the surface of a polymer particle.