Abstract: Based on the plane st ress full-elastic model and 3D numerical model , 2D and 3D methods of calculatingthe failure rotating speed of the composite flywheel were established. In these methods , the maximal tension st resscriterion of orthot ropic material was adopted. Two st rength criteria were adopted in the 3D method , namely averagevalue criterion and maximal value criterion. High speed rotating and failure experiment was developed on three flywheels and the failure occurred at the interface between mandrel and flywheel. The test result s show that the actualfailure speed is very close to the theoretical failure speed and the 2D and 3D methods are reliable. The theoreticalfailure speed calculated by the 2D method is comparatively higher. And the actual failure speed is in between of thetheoretical failure speed calculated by the 3D method. It shows that the 3D method is more accurate.