An automatic optical inspection (AOI) method for inspecting defects on a surface of an object is provided. The method includes: providing at least two different illumination systems; acquiring, by at least one detector, at least two pieces of image information of the object, each piece of image information being acquired under illumination of a corresponding one of the illumination systems; obtaining at least two pieces of surface defect information of the object by analyzing the acquired at least two pieces of image information using a computer and storing at least one of the obtained at least two pieces of surface defect information by the computer; and combining, by the computer, all of the at least two pieces of surface defect information to de-duplicate the at least two pieces of surface defect information and obtain a piece of combined surface defect information.