Research of the scattering of electromagnetic waves by charged particles is significant for the thorough understanding of electromagnetic field and the detection of the clouds and lightning warning. According to the theory of the Mie scattering of the charged particles and the characteristics of the Rayleigh scattering, the simplified scattering coefficient is derived, that is related to the surface conductivity and the electromagnetic impedance in vacuum. The results calculated by both Mie and Rayleigh formula for particles with a small size parameter are concordant. The charges carried on the surface of the particles increase the surface conductivity. When the surface conductivity reaches magnitude of millisiemens, it will have obvious effects. As the surface conductivity increases, the scattering efficiency will have bigger change. When the conductivity reaches a certain value, the ratio of scattering efficiency of the charged and neutral particles with a small size parameter tends to be stable. For the charged droplet, the ratio will tend to be twenty four which is related to the dielectric constant of the particles.