The invention discloses a Mirau-type wide-field-of-view interference microscopic objective optical system. The system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a reference board and a beam splitter board, which are arranged in sequence along the same optical axis. Illumination light passes through the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the reference board in sequence and is split into two beams by the beam splitter board, wherein one beam is incident to the surface of a reference flat plate and is reflected, and the other beam is incident to the surface of a member to be measured and is reflected; the two beams of emitting light are overlapped on the beam splitter board and interference occurs; and microscopic characteristics of the member to be measured is analyzed according to generated interference fringes. Magnification of the system is 0.5 X; numerical aperture is 0.015; entrance pupil diameter is 12 mm; focal length is 400 mm; parfocal distance is 280 mm; and field of view can reach 48 mm. The optical system is simple in structure and good in imaging quality, is suitable for coherent scanning interferometry and can be used for measuring three-dimensional shape of an uneven surface.