Abstract: A workpiece measuring machine adapted to measure a workpiece under test is provided. The workpiece under test includes an assembly surface and an appearance surface. The workpiece measuring machine includes a bearing base, a height measuring device and a calculation device. The bearing base is adapted to bear the workpiece under test. The height measuring device is movably disposed at a side of the bearing base and adapted to measure heights of the assembly surface and the appearance surface. The calculation device is electrically connected to the height measuring device so as to calculate a height difference between the assembly surface and the appearance surface. A measuring method and a calibration method of sectional difference of casing of workpiece are also provided.