Based on Lorentzian profile auroral theoretical formula of interference intensity, modulation and optical path difference (OPD), measurement of upper atmospheric wind field can be achieved. Four interference intensities are obtained by “four-intensity way” to detect upper atmosphere wind speed, temperature and pressure based on Lorentzian profile. The modified Sagnac interferometer (MSI) has been put forward to substitute Michelson interferometer for wind field; the benchmark optical path difference (OPD) formula of MSI has been presented. The technique of coating pyramid prism (CPP) has been put forward too. By the technique of coating pyramid prism's anti-reflection coating for three faces, four intensities can been obtained through stepped optical path difference of λ/4 at the same time. A simulation test has made: when the symmetrical light of Kr 557.0 nm to the two-faces CPP's vertex of 60° angle, there are two imager speckle patterns on the CCD camera of 768×576, copying the two imager speckle patterns there are four interference intensities in a periods, so Lorentzian profile auroral upper atmospheric wind field can be achieved.