Based on the optical rotatory dispersion and zero reflection of the p-polarization light at the Brewster angle, a novel optical filter that employs only one NaBrO3 crystal and one polarizer are proposed and demonstrated. Performance of the optical filter is studied both theoretically and experimentally. Results show that the green light is becomes nearly extinct when the angles of the polarizer are set at 80o and 260o, whereas the red light becomes nearly extinct when the angles of the polarizer are set at 116o and 296o. Isolation of more than 8 dB can be achieved. The measured extinction ratios are 12.3 and 12.6 dB for green and red lights, respectively.