The defect evolution is investigated for high-reflective coatings under multiple irradiations with an improved statistical model. The fatigue effect is observed with an increase in the shot numbers, but the fatigue process will not endure and it tends to be saturated when the number of shots reaches a certain level. With the addition of a bilayer unit, the defect density distribution of the high-reflective coatings is obtained. Two defect types are identified, and the differentiation of the high-damage precursors can well explain the decrease of the laser-induced damage threshold, as well as the saturation effect.