This paper proposes a new high-frequency narrow-band filtering mechanism using the internal resonance of an inverted T-shaped resonant structure. The proposed filtering mechanism is theoretically analyzed by combining the multi-scale method with the numerical iterative algorithm. For potential narrow-band filtering application, the influence laws of parameters related to the inverted T-shaped resonant structure on the internal resonance response characteristics are systematically studied. Two possible filtering systems integrated respectively with MEMS Switch and Double Frequency Circuit are further considered and discussed. The above two filtering systems have advantages of a good amplitude stability, a clear edge distribution in the passband frequency domain, and a strong suppression ability outside the passband frequency domain.