We use an ultra-spectral resolution spectrometer for mesospheric OH radicals to obtain a high resolution direct solar spectrum in the wavelength of 308 nm based on spatial heterodyne spectroscopy techniques and the sun direction equipment. By removing the dark current and baseline, phase correction and Fourier transform, we get spectra from interferogram data. The results are in good agreement with radiative transfer model simulation. These results provide experimental data for orbital high resolution solar spectra and scattering signal detection.