Abstract: An edge detection method of moving plate objects was designed by means of the image gathering function of a linear array CCD. The hardware structure was effectively simplified with a parallel beam projector as an illuminating source, an AVR single-chip computer to drive the CCD and to dispose the detected results. The measurement circuit and the binarization principle of CCD output signals are introduced. The design plan of the hardware and software are also provided. The experiment shows that the measuring accuracy of this instrument is better than 0.03mm，and the response time is fewer than 0.2ms.