Metamaterials are artificial media structured on a size scale smaller than the wavelength of external stimuli, and may provide novel tools to significantly enhance the sensitivity and resolution of the sensors. In this paper, we derive the dispersion relation of cylindrical dielectric waveguide loaded on double negative metamaterial (DNM) layer, and compute the resonant frequencies and electric field distribution of the corresponding Whispering-Gallery-Modes (WGM). Theoretical results of resonant frequency and electric field distribution are in good agreement with the simulation results. We show that the DNM sensor based on microring resonator possesses higher sensitivity than the traditional microring sensor since the amplification of evanescent wave, and with the increase of metamaterial layer thickness, the sensitivity will be increased greatly. It might open an avenue for designing perfect sensors.