In order to maintain a high machining accuracy and a constant speed feed-rate in CNC machining and improve the machining capability of CNC in handing complex part，the complicated interpolation algorithm needs to be used in CNC interpolation，which is time-consuming for large amount of computation，thus the machining speed is influenced. To solve this problem，based on the principle of parametric curve paths CNC interpolating，it is pointed out that Taylor series and iterative algorithm，given curve，using the chord length and the interpolation point，accurately calculate the next interpolation points. In the number of iterations and iterative error are less than the set value when the end of the iteration，next interpolation points can be calculated，and keep the current point and speed，otherwise continue iterative algorithm until they meet the requirements，feed-rate-controlled method based on iterative algorithm for curve real-time interpolation has also been given. The simulation results demonstrate that the proposed algorithm can satisfy the machining of a variety of different parametric curves. Compared with the conventional interpolation algorithm，it features are high university for machining，small computational a mount small feed-rate error and high computational accuracy，thereby greatly shorting the processing efficiency.