A linear discrimination function (d(w, x)=w′x) is presented to classify two aircrafts (the bomber and the fighter) with rotation invariance. There are 72 rotation images (patterns) for each aircraft, in which 9 rotation patterns are used as the training set and the other 63 patterns are used as the test set. The original weights {wij} are obtained by one of the training pattern of the bomber subtracting one of the training pattern of the fighter. To improve the correctly recognizing rate, a modification of the correctly weights is carried out by the wrong recognized training patterns. In order to opto-electronically implement, the weights {wij} only have five values (-2, -1, 0, 1, 2). The results of the computer simulation state that the correctly recognizing rate reach to 95.8%. A opto-electronic hybrid system is presented to implement this linear discrimination function for recognizing the objects with the rotation invariance.