Abstract: C language programming of SCM is a course with strong practice, which is mainly programmed by Keil software.In teaching, theoretical teaching and practical teaching should be put together. And the practical teaching should verify the correctness of theoretical teaching. The C language of SCM mostly uses Keil software to program. Keil software is currently popular with microcontroller compiler software. When having a class of microcontroller C programming language design, Keil software serial debugging technique is to introduce into the teaching, and add serial communication program and the sentence of printf in SCM C programming. Then one can use the serial debug window of Keil software to display the results of theoretical knowledge in textbooks with C language of SCM. This reform strengthens persuasion of theoretical knowledge, verifies the correctness of the program and makes the teaching process more rigorous.