The currently existing five-axis CNC machining systems tend to employ linear interpolation algorithm in machining, which will result in nonlinear errors and abrupt tool orientation changes due to ignoring tool orientation interpolation. To overcome those disadvantages, a tool path interpolation method that takes tool orientation interpolation into consideration is introduced. The curves produced by tool orientation fitting algorithm are C2 continuous, and are lying on the unit sphere. NURBS(Non-Uniform Rational B-splines) curve fitting method is used to fit these points and NURBS interpolation is also used to obtain the position of each axis in real-time. The performance of the proposed method is demonstrated by a practical example. Experimental results show that the tool paths generated by the proposed method have better machining accuracy and abrupt, large movements of rotating axis can be avoided during machining.