First, a composite structure composed of gold grating, medium, and gold film is designed on the end face of optical fiber, and the variation of various resonance modes with the thickness of medium layer and their field distribution characteristics are studied. Then, the waveguide resonant modes limited to the nanometer spacing between the gold grating and the gold film are studied. The different order of nanometer resonance effects are studied by the variation of the reflection spectrum and the electric field distribution characteristics of the resonant mode. In addition, the simulation calculation of gold grating width, thickness, and cycle, intermediate medium layer refractive index and thickness of gold film changes on the spectral characteristics and the effect of nano-resonator based on waveguide mode interference phase difference formula of the qualitative analysis of the change of resonance frequency, and calculate the obtained nano-cavity on the sensitivity of the refractive index and the length of cavity medium. Finally, a micro-displacement platform is built to verify the Fabry-Perot interference formed spectrum with the distance between the optical fiber end face and the gold film, and the realization scheme of the optical fiber end face nano-resonance structure is proposed.