In the paper, the optical properties of GaN wedge-shaped quantum dot (WSQD) under influence both pressure and electron-phonon (e-p) interaction have been investigated. To this end, the energy difference and dipole matrix elements are evaluated by considering the effects of e-p and pressure. Then, the refractive index changes (RICs) and absorption coefficients (ACs) are evaluated. It is deduced that the energy difference and dipole matrix elements reduce by considering the e-p and pressure effects. It is resulted that the pressure enhances the e-p effect on the energy difference. The ACs and RICs move to lower energies by considering the e-p and pressure effects. The RICs and ACs are raised in the presence of e-p effect whereas they are reduced with considering the pressure. With considering the e-p and pressure effects on total ACs, it is seen that the peak of AC splits into two peaks.