1. A method for extracting image salient curve, comprising steps of: a. drawing a curve on an image from which a salient curve is to be extracted along a salient edge thereof; b. obtaining short edges in the image; c. calculating a harmonic vector field by using the drawn curve as a boundary condition; d. filtering the short edges in the image by using the harmonic vector field; e. updating the vector field by using the short edges left in the image as boundary conditions; and f. obtaining an optimal salient curve of the image by minimizing energy of a spline curve in the vector field.