Based on the displacement curve of four CNC Numerical Control System 1 Teachers Campus,Guangzhou Technology Teachers College, Li Li-bin 2 Guangdong Industry and trade Professional Technology College, Zhao Wen-long 3 guangdong university of technology,Gao-jian Abstract: To adding the control method reducing the speed, in CNC, the population having wielded go along in numerical control system introduces that. The population structure adding the method numerical control system reducing the speed has carried out the part introducing , including hardware and the software on development four time of displacement curves. Have been used for and then explanation to the method applying concretely in adding the system reducing the speed in , have been in progress and by adding the method reducing the speed one processes an example , face to face common several kind verifying and comparing. Keywords: Add the control method reducing the speed Four time of displacement curves add the method reducing the speed CNC numerical control system