Objective As a novel surface mode, Tamm plasmon polaritons (TPPs) can be directly generated by the incident light with any polarization on the interface between metal and a distributed Bragg reflector (DBR) because its dispersion curve lies inside the light cone. Significantly enhanced energy distribution on the metal -DBR interface makes TPPs a potential candidate for nanoscale sensor devices. However, highly localized energy also prevents TPPs from touching the outside medium. In order to improve the sensing sensitivity of TPPs to the ambient medium, a triplelayer combinative structure has been proposed in this study, which is constituted by a metal film sandwiched between a metal grating and a DBR section. In this configuration, TPPs can be effectively excited on the interface between DBR and the metal film with a proper thickness, and a fraction of the localized energy induced by TPPs can penetrate the metal film into the grating slits to produce the surface plasmon polariton (SPP) modes supported by the metal slits. A quasi -Fabry -Perot (F -P) resonance of SPPs can be generated by a proper incident wavelength, and the highly localized energy accumulated through the F -P resonance can be employed to sense the refractive index of the ambient medium .