In the present work static dielectric constant (ε0), refractive index (n) and density (ρ) have been experimentally determined for binary liquid mixture of 1-Propanol (1-PrOH) with benzonitrile (BN) over the entire concentration range of mixture composition (0.0 →1.0) at constant temperature 303.15 K. Static dielectric constant (ε0) and refractive index (n) for the binary mixture have been measured using high precision LCR meter (2 MHz) and Abbe’s refractometer respectively. Molar refraction (Rm), atomic polarization (PA), molecular radius (r) and polarizability (α) and internal pressure (Pint) for each the binary mixtures were calculated from the measured values of refractive indices and densities. Using the experimental data various excess parameters namely; excess static dielectric constant (ε0) E , excess refractive index (n)E , excess density (ρ)E , excess molecular radius (r)E , excess atomic polarization(PA) E , excess internal pressure (Pint) E have been computed and discussed in terms of hetero-interaction (i.e. interaction between unlike molecules). These excess parameters were fitted to the Redlich-Kister polynomial equation to derive the binary coefficients and standard deviations. In order to predict the static dielectric constant (ε0) and refractive index (n) for binary mixtures several mixing rules were applied and their validity have been tested for the same