Spontaneous and piezoelectric polarization are known to be the key effect on the electronic and optical properties of polar heterostructures. This effect modifies the electronic states and optical absorption spectrum. Howerver, the strength of the polarization field is controlled by the composition. We present variational calculations of the eigenstates  and transition energy of the electrons in an GaN-based parabolic quantum-well for the decrease of piezoelectric fields. The ground state electron density profile hardly changes, whereas the first excited state one significant changes. We show that the redshifts of the absorption spectrum peeks by the electron transition between the ground state and the first excited state in this quantum-well.