A probabilistie progressive failure analyzing method is applied to estimating the reliability of asimply supported laminated eomposite plate with an initial imperfection under bi-axial eompression load.Theinitial imperfection and the strength parameters are considered as random variables.Ply-level failure proba-bility is evaluated by the first order reliability method(FORM)together with the Tsai-Wu strength eriterionand Tan criterion.Current stresses in the laminated structure are calculated by the classical lamination theorywith the stiffness modified based on the last step ply failure.Probabilistieally dominant ply-level failure se-quences leading to overall system failure are identified,based on which the system failure probability is esti-mated.A numerieal example is presented to demonstrate the methodology proposed.Through parameter stud-ies it is shown that the deviation of the initial imperfeetion and some of the strength parameters largely influ-ence the system reliability. A probabilistie progressive failure analyzing method is applied to estimating the reliability of asimply supported laminated eomposite plate with an initial imperfection under bi-axial eompression load. by the first order reliability method (FORM) together with the Tsai-Wu strength criterion and Tan criterion. Current stresses in the laminated structures are calculated by the classical lamination theory with the stiffness modified based on the last step ply failure. Probably idealized ply-level failure se-quences leading to overall system failure are identified, based on which the system failure probability is esti- mated. A numerieal example is presented to demonstrate the methodology proposed. Through parameter stud-ies it is shown that the deviation of the initial imperfecttion and some of the strength parameters largely influ-ence the system reliability.