Abstract: In order to investigate the effect of fiber wrinkle on the internal pressure-bearing capacity of filament-wound composite case, a computational model for predicting the burst pressure of composite case with fiber wrinkling was proposed based on Classical Lamination Theory and differential element method. The influences of fiber wrinkle occurring in longitudinal fiber-wound layers on the equivalent stiffness, stress distribution, tensile strength and burst pressure were quantitatively investigated. The results indicate that fiber wrinkling results in non-uniform fiber tensile stress distribution and locally elevated stress levels, as well as high interlaminar shear stress in longitudinal wound layer, which can shift fiber failure mode from tensile failure to tensile-shear coupled failure. When the fiber wrinkling amplitude is three times the fiber-wound layer thickness, the fiber tensile stress increases to nearly twice that in a wrinkle-free structure. The fiber wrinkling in longitudinal fiber layers can significantly decrease the axial tensile stiffness and tensile strength of the filament-wound case, while having only a slight effect on the hoop tensile stiffness and tensile strength. When the fiber wrinkling amplitude equals three times the fiber layer thickness, the axial elastic modulus and axial tensile strength are reduced by about 45% and 80%, respectively, while the hoop elastic modulus and hoop tensile strength are reduced by about 4% and 5%, respectively. The effect of fiber wrinkling in longitudinal wound layers on burst pressure of filament-wound case is related to wrinkling severity, number of wrinkled layers, fiber layer thickness and winding angle. When the thickness of the longitudinal and hoop wound layers are similar, as the wrinkling severity increases, the burst pressure remains nearly constant at first, and then decreases rapidly. The burst mode changes from initial failure of hoop fiber layer to initial failure of longitudinal fiber layer .