对可以用函数公式描述的工件轮廓或曲面进行数控加工，这是数控加工系统重要的功能。在数控车削中，利用宏程序完成各种公式曲线轮廓的数控加工，是数控车加工实训、数控技能竞赛实操必考核项目。但是对基础薄弱的中职学生来说，很难理解宏程序的编程思路。本文通过教学实践总结出的经验公式，非常好的解决了这一教与学的难题。-Formula that can be described with the function or contour surfaces for NC machining, CNC machining system, which is an important function. In CNC turning, the use of macros to complete contours of the formula curve CNC machining, CNC lathe is the training, skills competitions practical operation of CNC will assess the project. But on the basis of weak vocational students, it is difficult to understand macro programming ideas. In this paper, summed up the experience of teaching practice, the formula is very good solution to this problem of teaching and learning.