Abstract: This paper discusses the application of PMC axis control in FANUC NC system 0i series, applies PMC axis control technology to control CTB domestic servo unit, realizes the function of arbitrary orientation of spindle, briefly expounds the basic principle of arbitrary orientation of spindle, the compilation of trapezoidal PMC, the setting of parameters and the realization process of arbitrary orientation function, and solves the problem of arbitrary orientation function of spindle in FANUC system. FANUC servo unit must be used to solve the problem of high price and provide readers with another alternative solution.