In this paper， we propose a new method for 3D discrete curve smoothing by adopting an intrinsic representation for discrete curves. With this representation， a piecewise 3D curve is defined by lengths of edges， angles between edges and the positive x-axis， and angles between edges and the positive z-axis. For a noisy curve， we first filter the two angle sequences of the curve by bilateral filtering method. Then， we obtain the smoothed vertexes of the curve by solving an objective function under the constraint of the two angle sequences. By this algorithm， not only can main features of the original curve be preserved well， but also the smoothed curve no longer suffers from shrinkage.