Abstract: Accuracy degree of mapping relation between curve parameter and feedrate affecting interpolation precision is neglected with conventional planning feedrate method generally.Aiming at this problem,a method of splitting the NURBS curve following its curvature monotonicity and thereby planning feedrate algorithm is proposed.First set the critical value of curvature; second analyze the curvature monotonicity of NURBS curve,and then split the NURBS curve into several sub-segments according its critical value of curvature,critical and transition points of curvature,and calculate arc length of each sub-segments; at last,considering the constrains owing to dynamical properties of machine tools,optimize suitable feedrate from critical points of curvature bilaterally to critical value and turning points of curvature with S acc/dec.Comparison results between the conventional and proposed planning algorithm indicates that the interpolation precision can be remarkably enhanced along with little prolonging machining time utilizing the proposed algorithm.