In he process of NC machining, the precise computation of machining graphical path is the key to guarantee machining precision. In curve fitting, it is difficult to fit curve just only using straight line. The combining both arc and line may get good fitting effect in fitting curve. But it leads to complicated calculation in fitting. Aiming at this problem, multi-dimensional fuzzy reasoning algorithm is proposed in this paper to optimize the calculation process and improve the fitting curve speed and accuracy. The designed multidimensional fuzzy inference algorithm makes the computation of the curve fitting simplicity and preciseness when the model structure is used in programming. Test results show that the designed way can well approximate the original graphics and well optimize the number of segment in the fitting process.