In our contribution, we have carried out a theoretical study of the transition characteristics of one-photon absorption (OPA) spectra of the folded conformation and the extended conformation of fluralaner. The electronic transitions in OPA are visualized with charge difference density (CDD) and transition density matrix (TDM) to explain the charge transfer via hole-electron distribution. We also analyze the transition dipole electric/ magnetic moment by using the isosurface (real space) and TDM diagram in order to determine the portions of molecules which have the most contribution in ECD spectra.