Abstract: Delamination in laminated composites with uncertain parameters was studied. Based on the interval mathematics, with uncertain parameters being modelled as interval numbers, an interval analysis method was proposed about delamination in laminated composites with uncertain parameters. The interval analysis was compared with the probability method with respect to the mathematical proof and numerical examples, which verifies the reliability. For a fixed pre-crack length or layer number, the upper and lower critical loads of DCB with uncertain parameters were obtained. It would provide reference for engineering design.