The Kepler-90 planetary system is known for its eight planets in a hierarchical configuration. This study uses frequency analysis to examine the system's orbital stability across different eccentricity intervals. The results reveal stability for low and medium eccentricities, with mean motion resonances (MMRs) identified between planet pairs Kepler-90b–90c and Kepler-90g–90h. The analysis explores the nature of these resonances, including libration, circulation, and intermittent behaviors of critical angles, contributing to the understanding of the system's dynamics.