An internal Brewster guided-mode resonance (GMR) filter is designed.For this kind of GMR filter,the Brewster reflection occurs at the interface of grating/waveguide layers rather than at the interface of air/grating layers.At Brewster angle of 60°,the GMR filter owns almost 100% reflection at the resonance wavelength of 800 nm with the full-width at half-maximum (FWHM) of 0.2 nm.Its angle response changing with the fabrication deviation is also discussed. An internal Brewster guided-mode resonance (GMR) filter is designed. This kind of GMR filter, the Brewster reflection occurs at the interface of the grating / waveguide layers rather than at the interface of air / grating layers. At Brewster angle of 60 ° , the GMR filter owns almost 100% reflection at the resonance wavelength of 800 nm with the full-width at half-maximum (FWHM) of 0.2 nm. Its angle response changing with the fabrication deviation is also discussed.