Static permittivity and relaxation times have been determined for four Schiff bases derived from 2-hydroxy-1-naphthaldehyde with o-substituted anilines in Dimethylsulfoxide (DMSO) solution by using a Time Domain Reflectometry (TDR) technique. The observations are taken at room temperature (30°C) in frequency range 10 MHz to 20 GHz. Fourier transform and least squares fit methods have been used to obtain dielectric parameters.The excess dielectric parameters have also been determined for the system. In the present investigation it is observed that there is change in dielectric parameters of the system with change in concentrations.