A novel ZH optical system and its' alignment research is presented in this paper. The ZH optical system consists of a first paraboloid

a mirror with two operational faces and 45° angle

a second paraboloid. The two paraboloids have a common focus plane. The mirror with two operational faces has a central small hole

the small hole is located at the common focal plane of the two paraboloids

the coefficient of obstruction of the ZH optical system minimized

the focal plane of the two paraboloids is the immediate real image plane of the ZH optical system

the central small hole can be used the aperture of the field of view and the aperture of the obstruction

the centre of the small hole is common axis with the optical axis of the two paraboloids. The two paraboloids can be installed from every side respectively

which avoid the difficult problem of assembly of the second mirror of the Cassegrain. There is an offset distance between the incidence optical axis and the shoot optical axis of the ZH optical system because of the mirror with two operational faces' thickness. The offset is compensated by parallel offset lens

which realize system common axis. The parallel offset lens are taken down when ZH optical system is assembled. Based on the ZH optical system

the MWIR polarization image optical system is assembled and the MWIR polarization image is presented. The ZH optical system can be used in the MWIR polarization imaging optical system and the SWIR polarization imaging optical system. The paraboloids and the mirror with two operational faces avoid the difficult problem of plating wide waveband anti-reflective coating in the surfaces of lens. The dual waveband polarization imaging optical system realize common aperture in its' first telescope because of the ZH optical system.