To extract slender object from image with strong interference, a method based on Snake is proposed by using centerline and width’s curve. Making use of the centerline symmetry of slender object, the contour is described by using two one-dimensional functions about centerline and width instead of two-dimensional expression. By evolving this two functions to meet the minimization energy of snake model, the object is accurately extracted. The symmetry of edge gradient is used, and a weighting function is mentioned to increase the image force. By this way, the interference can be avoided and iterations can be reduced. The improved algorithm reduces the number of control points and the size of calculation, and the results can be obtained automatically and fast. Experiments show that the improved algorithm is effective.