The cumulative effect of nanosecond multi-pulse irradiation on the dielectric coatings in atmosphere and vacuum environments was investigated. The laser-induced damage thresholds (LIDT) and the life span submitted to multi-pulse irradiation in two environments were compared. For both environments, we observe a decrease in laser-induced damage thresholds (LIDT) when shot number increase. However, the fatigue effect under repetitive shots under atmosphere environments and vacuum cases leads to different speeds of degradation. The correlative theory models were built to explain the experimental results. (C) 2011 Elsevier B. V. All rights reserved.