Computer vision has already been widely used in engineering. The circle detection using image processing means significantly in engineering. In order to auto-detect the circle and accurately extract the centre and radius, an improved Hough transform algorithm for circle detection is proposed. The image border is filtered to get the continuous borders. And then the continuous borders are sequenced and equal divided. Only three points are chose for computation and three dimension parameters will be reduced to one dimension, which saves the computational time, memory sources and improves the accuracy. Experiments show the proposed method can realize real time detection and meet the reality needs.