The invention discloses an optical teaching aid. The center portion of a lens model is provided with an optical center rotation shaft, the optical center rotation shaft is provided with a main opticalshaft object line, a left end of the main optical shaft object line is provided with a model, left and right ends of the main optical shaft object line are provided with ray direction indicators, anupper end of the lens model is provided with a refraction light rotation shaft, the refraction light rotation shaft is provided with a rotation shaft sleeve, the rotation shaft sleeve is provided witha refraction connection tube, a port of a right end of the refraction connection tube is internally provided with a refraction light object line, a port of a left end of the refraction connection tube is internally provided with a reflection light object line, during demonstration, a lens model suction cup, a flat light object line suction cup and a main optical axis object line suction cup are sucked on a blackboard to replace a lens and an object, the object lines are utilized to replace light, multiple rigid light path diagrams drawn on the blackboard are converted into flexible and realistic object patterns, and students are facilitated to visually see each imaging rule of the lens.