The purposes of the research were to create and efficiency validation of computer assisted instruction focused on the practice to CNC Tuming of the standard 90 / 90 and analyse the student leaning achievement of the student after by using computer assisted instruction.The subjects in the study were 23 first year diploma students enrolled in Computer Numerical Control Rajamangala of Technology. North Bangkok Campus. The Researcher using the experiment by let the students do until test before class. And then study by using computer assisted instruction focused on practiced to CNC Turning. After that let students do the unit test again at the class and calculate to find out the efficiency of the computer assisted instruction and analyse the leaning achievement of students after study. The research result revealed that the efficiency of the computer assisted Instruction was efficient in standard 90 /90 Moreover after learning achievement At significant level of 0.01