We theoretically investigate the propagation of surface plasmon polaritons (SPPs) for the metal-dielectric-metal slot Bunk Bed waveguide coupled to a disk cavity filled with gain material.The transmission and reflection characteristics of the resonant structure are numerically analyzed based on coupled-mode theory.The influence of structure parameters on the spectra of transmission is investigated using a finite-element method.In addition, the incorporation of gain medium can compensate for the loss from metal and, thus, enable the loss-negligible SPP propagation in near-infrared wavelengths, which makes a novel approach of optical switches and lasers based on SPPs Gels possible in the planar optoelectronic compact integration.