This study proposed a method of importing Scale-invariant feature transform (SIFT) to Automatic Optical Inspection System (AOIS) to improve the tolerance of object position and rotation detection in AOIS, to increase the precision and decrease the implementation cost. This study uses the scale & rotational invariant of SIFT to locate the position and the angle of object to increase the precision of image matching, and replace the step of locating the object to designated position with robotic arm and conveyor of AOIS. And decrease the AOIS implementation cost.