Two Metal-Insulator-Metal (MIM) waveguide structures that consists of T-type cavity and baffle were proposed, and they are the positive T-type cavity structure and the inverted T-type cavity structure respectively. The transmission characteristics of this structure were calculated by using the Finite-Element Method(FEM). The simulation results show the double Fano resonances for the positive T-type cavity structure, and the resonant wavelength can be easily tuned by changing the length and the height of the T-type cavity.The structure would be helpful for designing the nano-sensor with a sensitivity of 1620 nm/RIU and the figure of merit of 5.4×104.By inverting the T-type cavity, multiple Fano resonances are observed in the waveguide with a sensitivity of 1560 nm/RIU and the figure of merit of 9.37×104. The waveguide structure may have wide applications in highly integrated optical circuits , especially for nano-sensor and spectral splitter.