Abstract: In an optical system,"cat eye effect" can be modeled as a focal lens system.Based on the model,with the property that it can reflect the input laser exactly back along the direction the laser incides,a "cat eye" system can be applied as an equivalent laser resonant mirror to achieve the laser resonance.At the same time,the equivalent reflectivity of the "cat eye" system has been calculated.The experimental results have also proved this point of view.The laser resonance has been obtained with deferent mediums at the focal plane of our simulated "cat eye" system and all these mediums have been destroyed by the focal laser spots.