The formulation of conductivity and dielectric susceptibility for the dust plasma at weak ionization is deduced by solving the Boltzmann’s equation and Shukla’s equation, which are the governing equations on dust particle charge and discharge processes, provided that the weak external electromagnetic field is imposed and the space dispersion neglected. The proper parameters of a solid rocket exhaust plume are then substituted into the derived formulae. The calculated results show that the radius and concentration of dust particles have significant influence on the conductivity and dielectric susceptibility.