These are many kinds of geometrical gauges used for calibration of machine tools and coordinate measuring machines (CMMs). A step-gauge is a kind of calibration gauge, It consists of many short block-gauges. Block-gauges were directly calibrated by an interferometer using method of exact fraction. The method, however does not apply to the calibration of step-gauges because of their complicated structure. The calibration works are very important missions in national metrology institutes (NMIs). We developed the step-gauge calibration system that consisted of a CMM and an interferometer. In this paper, we describe the performance of a CMM system combined with an for step-gauge calibration and the evaluation of the measurement uncertainty. The uncertainty in measurement using this system is about 1.0μm(k=2) for 1-meter measurement.