A metal-insulator-metal structural filter, which comprises two oblique symmetric rectangular ring resonant cavities and a waveguide, was built using a boundary coupling approach based on surface plasmon polaritons. A finite element method was employed to simulate and examine the filter, and the magnetic field distribution map and transmission curve were generated. The findings demonstrate that the filter’s maximum transmittance in the pass-band is 0.969, and its minimum transmittance in the stop-band is close to 0. This filter also has a wide pass-band and stop-band features, and a smooth transmission curve. The filter’s transmission curve can be red-shifted or blue-shifted by adjusting the structural parameters, and by setting certain structural parameters, the function of the on-off of the second and third communication windows of the filter can be controlled selectively while keeping the first communication window passing through. Thus, the filter can be employed as a band-pass/band-stop filter, which has crucial applications in high-density integrated circuits and optical fiber communication. furthermore, an electro-optic switch function can be accomplished by enhancing the structure and adding the electro-optic material DAST.