A region growing algorithm based on the grey relational analysis was proposed. By means of calculating the two-dimension grey absolute relational grade, the original image was turned to a grey relational image only containing the edge information. Meanwhile, by the region marking of the grey relational image, the centers of small defects were obtained. And these centers were used as the seeds pixels to do the region growing and the detect extracting in the grey relational image. The experimental results indicated that the new region growing algorithm could suppress the background noise, simplify the calculating process, and meet the requirements of the real time extracting effectively.