Abstract: A automatic resolution measurement system of Cathode Ray Tubes (CRT), display tubes has been developed. The width of a scanning line displayed at screen can be measured accurately and quickly by an area array Charge Coupled Device (CCD) camera with a microscope lens. The system has voltage auto-adjusting functions of optics focusing and CRT's focusing. Measuring results show that the auto-adjusting improves the precision and efficiency of the measurement effectively.