In this paper,first,a method to determine the initial position of smooth transition of thread is discussed by taking the linear acceleration /deceleration as an example. Then,according to the basic principle of thread cutting,an improved method of re-calculating the acceleration or the pitch increment is analyzed to ensure fixed transition time and length. Thus,an interpolation method for the smooth transition of multi-sect continuous thread is proposed. Simulation and processing results show that,when the proposed method is applied to the cutting of multisect continuous thread with different pitches or tapers,no significant embossment and change of the processing track is observed,and the smooth transition of a two-sect thread is successfully achieved,which means that the proposed method is of high accuracy,stability and repeatability.