The evolution of gear measurement technology in the past 100 years is fully reviewed, and 6 key issues related to gear metrology are listed. Emphases are laid on the development of gear measurement principles, the evolution of technical measures realizing them and the interpretation & utilization of measurement results. Meanwhile, the principle, configuration and features of present-day CNC Gear Measuring Center are introduced. A few of new phenomena in the field of gear measurement technology are remarked, and some research topics in the near future are proposed.