The purposes of the research were to create and find efficiency validation ofcomputer assisted instruction focused on the mold plastic injection making kind two plate for the standard 90/90 and analyze the students learning achievement after using computer assisted instruction. The samples were the 15 first year diploma tool & die students Rajamangala Institute of Technology North Bangkok Campus. The researcher experimented by using pretest and then using the computer assisted instruction focus on the mold plastic injection making kind two plate mold base make mold and adjust next the students did the posttest. After that the researcher calculated to find the computer assisted instruction efficiency and analyzed the students learning achievement after studying. The result revealed that the computer assisted instruction efficiency was efficient for standard 90/90. And after studying by using computer assisted instruction the students learning achievement increased significantly at 0.05.