Abstract: In order to speedily get the edge curve of micro-part image with high accuracy, a new algorithm based on sub-pixel edge location is proposed. Differing from the usual algorithm of sub-pixel edge detection, the proposed algorithm extracts the sub-pixel edge points directly without the need for fixing the edge location aforehand, so the less time is spent and the processing speed is improved. In addition, a new sorting method of image coordinates is applied to link the disordered edge points according to a certain clockwise order and a two-step image denoising method is used to consist with the micro-part image structure. To show the effect of the proposed algorithm, a few of experiments has been done to test the processing speed and accuracy. The experimental data show that the processing time is generally less than 1 s and the edge location accuracy is better than half-pixel.