Theory analysis of the photoionization phenomenon based on the electronic structure calculations has provided a powerful tool for obtaining the photoionization cross-sections. Krylov et al. obtained the Dyson orbital by the EOM-CCSD wave function and calculated the photoionization cross-sections by photoelectron matrix. The theoretical photoionization cross-sections were obtained by using coulomb wave to describe the emitted photoelectron, the results of some atoms and small molecules are in good agreement with the experimental values under the selection of appropriate effective charge. Lucchese et al. has computed PICS of CF4, 31 SF6, and N2 using the single-channel frozen-core Hartree-Fock (FCHF) assumption. Kai et al. improved the description of near-threshold photoionization based on of FCHF by multiplying the Franck-Condon overlap envelope with the transition moments. The discrepancy of the computed PICS for a dozen of testing molecules was estimated as less than a factor of 2. In this present study, the SVUV-PIMS was used to measure the PICS of benzonitrile and o/m/p-cyanotoluene from threshold to 14 eV. I onization energies of the species have been obtained by state-of-the-art theoretical methods as well. The FCHF method was used to simulate the photoionization cross-sections. Our goal is not only to provide necessary data for distinguishing product yields of the reaction of toluene + CN, but also to shed light on the PICS of CN substituted aromatics. The CN group has been regarded as an indicator for observing aromatic compounds in the interstellar medium due to the large dipole moments resulted from the CN substituents.