Abstract: The parametric vanational principle (PVP) is powerful to solve the nonlinear unspecified boundary problems in continuum mechanics. By the PVP, this paper studies the elastic-creep-damage problem. The proposed principle, a development of optimum control theory, is to minimize a constructed potential energy functional under the constrained conditions which are converted from the creep-damage equations. The mathematical proof of principle is given. Also, the paper quotes the results of creep experiments of 2.2...