Abstract: As an important kind of embroidery stitches, the spiral stitch fills an arbitrary shaped region along a uniform spiral curve, approximately parallel to the region’s outline, from the interior to exterior.In the algorithm,contour-parallel offset lines are first constructed to for m equidistant closed loops and then linked to get the continuous spiral curve.Regions are organized into a binarytree and the spiral curves in these regions are connected recursively to form the global stitch path based on the binarytree.Experiments show that the embroidery generated by this algorithmis fine.