Studies on first-passage failure are extended to the multi-degree-of-freedo
m quasi-non-integrable-Hamiltonian systems under parametric excitations of
Gaussian white noises in this paper. By the stochastic averaging method of
energy envelope, the system's energy can be modeled as a one-dimensional ap
proximate diffusion process by which the classical Pontryagin equation with
suitable boundary conditions is applicable to analyzing the statistical mo
ments of the first-passage time of an arbitrary order. An example is studie
d in detail and some numerical results are given to illustrate the above pr
ocedure.