Acceleration is discontinuous in the traditional acceleration and deceleration algorithms such as the linear and the exponential,which cause flexible impact in NC machining.However,the jerk of S-curve acceleration and deceleration is step change,which confines the flexibility.So,a kind of polynomial acceleration and deceleration control method is proposed,which guarantees the acceleration and jerk are continuous and makes the CNC system more flexible.This algorithm is analyzed and discussed the feedrate profile planning in detail.Simulation is performed to verify the advantage of the proposed method.