An electrically controlled double wavelength tunable filter based on lithium niobate (LN) is designed. Double wavelength of orthogonal polarization filter is achieved by etching Bragg grating on the Ti-diffusion LN waveguide, which supports transverse electric (TE) mode and transverse magnetic (TM) mode. The refractive index distribution and therefore the Bragg wavelength can be fast tuned by using electro-optic effect in LN. The performance of waveguide grating filter is analyzed and results show that the grating with 1/2 etching duty cycle and less than 15°etching angle has the best filter characteristic. The reflectivity and bandwidth increase with the etching depth increasing. Double wavelength filter achieves 15.6 pm/V sensitivity for TE mode, 5.5 pm/V sensitivity for TM mode by adding the transverse electric field on waveguide grating.