Abstract: The approach to implementing calibration with precision of micron in millimeter-scale work volume is put forward in this paper: the method for driving 3D sample block through motion part and reading 3D coordinates through 3 sets of microscopic camera system is adopted to implement calibration with precision of micron in millimeter scale work volume; Light distribution device consisting of four pieces of right angle prism and 3D sample block consisting of three pieces of 2D rulers of 8mm×8mm with precision of micron are taken as sample standard; The calibration results are given finally.