Flake-like diatomite was used as forming templates to prepare the core-shell functional particles by the electroless silver plating method. The effects of electroless plating process on the silver content and surface morphology of diatomite were discussed. The dielectric properties of silver-coated diatomite particles were also analyzed. The results indicate that the silver content of diatomite increases with increasing plating time and load. At the silver content of 34.65% (mass fraction), the silver coating is fairly homogeneous, continuous and compact, and the micropores on the surface of diatomite are completely covered by the coating. The dielectric properties of silver-coated diatomite particles are related with silver content, coating morphology and volume concentration. Furthermore, the imaginary parts of dielectric constant of all the samples are lower than the real parts. It shows that all the samples do not exhibit percolation phenomenon.