Abstract: Motivated by the observation that each knot interval should be of the same modeling ability,a knot placement algorithm based on equally spaced geometric information for B-spline curves is proposed.In the algorithm,a few of knots are determined according to the principle that each knot interval is of the same amount of geometric information at the initial iteration.In order to improve the modeling ability of the B-splines,the knot interval needed to be refined is determined by the last fitting errors and the new knot inserted is placed to equally space the accumulated geometric information in the knot interval.Via the adaptive knot placement algorithm,approximated curve with specified tolerance can be produced rapidly and efficiently.Several models with distinct geometric complexities are tested to demonstrate the efficacy of our algorithm in fitting curves.Comparing to other two available methods,more accurate results can be obtained by our method with the same number of control points.