The purpose of this study is to develop a CAD/CAM system for automatic creation and manufacturing of three dimension objects. The computer system used in this study made RAM 2M, CPU 80386, VGA graphic card. The results in this paper are as follows ; 1. By interconnect PC(personal computer) and NC(numerical control) milling machine with RS232C connector, we was constructed with CAD/CAM system. 2. The developed algorithm in this study is able to be design of three dimension object on the computer CRT and manufacturing of NC milling machine. 3. Because of design and modifying on the PC of objects, we can be saving time, cost and improvable precision of objects. 4. Essentially, we expect industrial accident to reduse according as we takes advantage of CAD/CAM system.