Abstract: Part accuracy in high-speed NC machining is often difficult to control, especial for large structure aviation. Small changes in some dynamic factors may lead to errors exceeding the allowable value. A method integrated machine on dynamic error factors and static geometric errors is presented to build the surface data of actual workpiece. Each servo axis movement is simulated and composed by kinematics of the joint bodies of the machine for calculating the actual position and attitude of the tool. The actual milling point is solved by the envelope theory and the final part of the surface is obtained by the surface forming method. A case study is analyzed through the "S" specimen sample, which is verified the composition of surface methods and get the milling error in influence of dynamic factors, such as the gap, the position loop and speed loop. This method can estimate the milling accuracy on large parts in advance, and help to adjust the dynamic parameters of the complex servo system. It provides a basis for better precision control effect and economic costs.