The invention provides a focal plane measuring device and defect detection equipment. The focal plane measuring device comprises a focus measuring
light source, a focus measuring marking plate, an optical
assembly, an imaging unit, a focal plane compensation structure and a
control unit; the focus measuring
light source is used for providing a first illumination
light beam which is obliquely incident, the focus measuring marking plate comprises at least one group of focus measurement patterns, each group of focus measurement patterns comprises at least three sub-marks, and after the first illumination
light beam is projected to the focus measuring marking plate, the focus measurement patterns are projected to the surface of a
test sample piece and generate a reflection
light beam; the focal plane compensation structure is located on one side of the imaging plane of the imaging unit and used for changing the transmission path of the reflected light beam, so that the imaging plane of the reflected light beam converged by the optical
assembly is located on the receiving plane of the imaging unit to form at least one group of
signal images, and each group of
signal images comprises at least three sub-patterns; and the
control unit acquires the vertical height of the
test sample piece according to the position of the at least one sub-pattern. According to the invention, coaxial measurement of the focus
measurement point and the defect detection point is realized, and the precision of focal plane measurement is improved.