Based on interconnected ion sputtering and cathodoluminescence spectroscopy, an optical spectroscopic strategy has been developed to profile depth-dependent polarization effects in an AlGaN multiple-quantum-well structure. Two emission bands at about 258 nm and 315 nm have been identified to originate from the quantum wells and Ga-rich domains, respectively, and their depth-dependent spectral characteristics reveal that the spontaneous polarization dominates the piezoelectric polarization in the quantum wells, and the emission wavelengths vary with respect to the etching depth due to interactions of the spontaneous polarization field with the piezoelectric polarization field and the surface charge induced electric field.