Optical fields can be bound at sub-wavelength level by surface plasma polaritons (SPPs) and dif. fraction limit can be broken through. SPP is regarded as one of the most hopeful carrier to implement integrated optical devices in nanometer level. A surface plasma waveguide filter with T-shape cavity structure is designed. And its filtering characteristics are analyzed by finite difference time domain (FDTD) method. The results show that the center wavelength of transmission spectrum can be changed by the changing of length and width of T-shape cavity. Q values of cavities can be adjusted by changing the distances between cavities and coupling waveguide.