A new baseline based shape coding algorithm is designed in this paper. Distance set and turning point are chosen from the shape contour，and coded by DPCM. So the 2 dimensional data can be described by 1 dimensional data，and K K reduce the bit streams effectively. The algorithm can adapt to every particular boundary trend，and gives a better reconstructed effect〖JP〗The reconstructed shape only has a geometrical error，and can overcome the ladder effect which always appears in the block based shape coding