A new fuzzy fast Hough transform is proposed to detect the circular boundary of Labyrinth disc aperture in an aeroengine.In the new algorithm,the circle detection problem is decomposed into two stages consisting of a 2D Hough transform to find circle centre and a 1D Hough transform to determine the radius.The 2D Hough transform performs a hierarchical approximation to the solution,starting from a coarse description of the parameter space.The coarse-to-fine search technique is used to reduce the computing and storage requirements of the Hough transform.And,the fuzzy vote technique is adopted to lessen the uncertainty that arise from edge pixel position error and gradient direction error.The circular contour detection results by the proposed algorithm are compared with the results by Standard Hough Transform and Randomized Hough Transform respectively.The experimental results show that the fuzzy fast Hough transform can detect the contour quickly and accurately.