Abstract: Taking the advantages of the localized and non-radiative properties of surface plasmon, we designed a novel filter by electromagnetic simulation software EastFDTD. This new kind of filter is formed by two metal ring resonators，the inner diameters of the two metal ring resonators are 175nm and 145nm respectively, and the wavelengths of surface plasmon meeting the resonance are different. Such characteristic of metal ring resonator results in outputting signals of 1.85m and 1.58m at different ports. The crosstalk between adjacent ports of this filter can reach -19dB with the output port width of 50nm. The result shows that this novel filter has more advantages than traditional filters in filtering performance, size and integration.