Abstract: A new algorithm for obtaining the centre of ellipse is brought forward. Some information about an ellipse is obtained by the coarse-location, and the edge points are detected by using Canny operator in the region of interest. Then the accurate edge points are acquired by Gauss curve fitting based on the information of the ellipse and the gray-distribution characteristics of the edge points. Finally, the filtering methods based on the curvature filtering and mean-filtering are carried out respectively to filter the isolated points and the noisy points, and the accurate centre of ellipse is obtained by least square method. The result proves that the new algorithm locates the centers of ellipses accurately and meets the need of real-time measurement.