<p>We present an analytical study of the asymptotic behavior of resonance-regime eigenvalues for the fractional Schrödinger operator under homogeneous Neumann boundary conditions. Our analysis reveals a distinctive phenomenon: in the resonance case, the eigenvalues of the fractional Schrödinger operator tend toward those of a finite-dimensional matrix <i>C</i> constructed from the Fourier coefficients of the potential. We derive a precise asymptotic characterization of these eigenvalues and further establish a refined error bound. Finally, we deduce a global spectral classification, showing that every eigenvalue in the asymptotic limit admits either a matrix-based resonance expansion or a standard perturbative form. This study clarifies how the operator’s spectrum near the diffraction plane is governed by the structure of the coefficient matrix, offering new insights relevant to mathematical physics.</p>