Polydimethylsiloxane (PDMS) was studied with different concentrations of boron in the structure of a polymer composite. Dielectric characterization of the prepared composite samples was analysed by dielectric spectroscopy. According to the outcomes of dielectric characterization, the increase in the B-doping ratio caused an increase in dielectric constant. Also, the lowest value of relaxation time was attained by 10% boron-doped PDMS. Besides, the studies of alpha -relation, relation time values and imaginary part of permittivity indicated that 10% boron-doped PDMS is found to be an optimized amount for a proper composite. Optimization of a tailored boron-doped polymer composite was realized and attained by dielectric spectroscopy throughout our work.