專利摘要：
A measurement, calibration and compensation system for machine tool includes a first positioning base; two first speckle image sensors for sensing speckle positions of an object holding unit at a first XY plane and a first XZ plane of the first positioning base before and after the machine tool is started for machining; a second positioning base; two second speckle image sensors for sensing speckle positions of a cutter holding unit at a second XY plane and a second YZ plane of the second positioning base before and after the machine tool is started for machining. Thus, the thermal expansion at all axes of the machine tool can be measured in a simplified and low-cost way, and the absolute positioning coordinates of all axes of the machine tool can be calibrated in real time to avoid reduced positioning accuracy due to the thermal expansion of the multi-axis machine tool.