A new interpolation method was presented to satisfy the requirements of CNC machining for complicated curves. Firstly, the proposed method used cubic uniform B-spline segments based on a real-time overlapping combination algorithm to fit complicated curves, and then an adaptive algorithm was provided to calculate the interpolation step size through taking the chord error, velocity and acceleration into consideration, which can provide a good performance for improving the contour accuracy and reducing the impact on machine.At last, a trajectory planning strategy was put forward to guarantee the trajectory in the interpolation process meeting the smoothed constraints of velocity, acceleration and jerk. The simulation results of interpolation experiments show that the presented method can ensure high-speed and high-accuracy of machining complex curves, and has a good smooth feature of velocity, acceleration and jerk. This method feasibility has already been proved in real CNC system.