The vibratory fatigue of some complex thin-walled structures undergoing random acoustic loadings is typically of multiaxial fatigue problems, and it is an effective approach to conduct the multiaxial fatigue damage analysis with Von Mises stress criterion. The probability distribution of Von Mises stress is investigated in this paper for structures under band-limited Gaussian white noise loadings. The hypothesis are proposed that Von Mises stress obey two-parameter Weibull distribution or Lognomal distribution, and the method for estimating the parameters of the two kinds of probability distribution are developed. As a result, the peak value probability desenty functions of Von Mises stress can be calculated, and these functions can be used as the basis for estimating the structural fatigue life. In the engineering application, by using coupled FEM/BEM method, the power spectrum density (PSD) of the vibrational stress response of thin-walled structures of an aeroengine combustor liner under random acoustic loadings is calculated, the probability distribution charactoristics of Von Mises stress are analyzed emphatically, and the results are comparetively validated by Kolmogorov-Smirnov(K-S) test.