The purposes of the research were to create and find out the efficiency validation of computer assisted instruction focused on the Plastic Injection Adjusting Machine and Injection Molding Maintenance for the standard 90/90 and to analyze the students’ learning achievement after using computer assisted instruction. The samples were 20 first year diploma tool & die students at Rajamangala Institute of Technology North Bangkok Campus. The students pretested and then studied by using the computer assisted instruction focus on the plastic Injection Adjusting Machine and Injection Molding Maintenance. Finally the students post tested. After that the data was calculated to find out the computer assisted instruction efficiency and analyzed the students’ learning achievement after studying. The result revealed that the computer assisted instruction efficiency was reached the standard 90/90 and the students’ learning achievement increased significantly at 0.05.