In order to improve spectrum resolution with the same size of the static Fourier transform interferometer, an orthogonal-wedge static Fourier transform interferometer is designed, which is made up by the two orthogonal-wedge for continuous optical path difference. According to the derivation of the optical path difference function with the tradition static Fourier transform interferometer and the orthogonal-wedge static Fourier transform interferometer, the structure of the two orthogonal-wedge is designed to increase the effective distance of detection for improving spectrum resolution of static interferometer. The simulation results show that the maximum optical path difference of the orthogonal-wedge interferometer is 0.323 4 mm, which is four times better than the traditional interferometer with 0.080 8 mm (optical path difference). Experimental results show that the orthogonal-wedge interferometer has the distortion of the interference fringes as a result of its detection principle, so it needs to be removed and filtering of the edge of the interference fringes. Using the WQF520 type spectrometer to comparative experiment for 800nm laser, the orthogonal-wedge interferometer error is less than 1 nm. This method can effectively improve the spectral resolution of the static Fourier transform interferometer.