The use of fisheye lens causes strong distortions in the resulted images.Accurate contour extraction of the fisheye image is a prerequisite for image correction.Traditional algorithm is ineffective to suppress the noises and can not be used when massive black pixels appear in the fisheye image′s circular outline area.So an improved tangent method of fisheye image contour extraction is proposed in this paper.The experiment results show that the proposed algorithm can exact the center and radius of the fisheye images and has obvious superiority of high precision and good real-time.Finally,a satisfactory effect of fisheye image distortion correction is achieved by applying spherical coordinate orientation.