During the preform loading of the Resin Transfer Molding (RTM) process, wrinkling in the fabric preform could occur and affect the quality of the bending properties. This study considers the effects that several wrinkled models with different wrinkled lengths in the fabric preforms of K618/R409 and K618/R235 composites have on bending properties. It is found that the experimentally measured values of the bending modulus and strength show a fair agreement with the predicted values using the modified rule of mixtures. Due to the effects of wrinkling, the bending modulus of the wrinkled models is larger than that of the normal model as a function of fiber volume fraction (Vf). Based on the energy method, the effects of wrinkling on the bending modulus are determined and described by the wrinkled parameters (α). The bending strengths of the wrinkled models have two fracture mechanisms as a function of the ratio of wrinkled length to span length (LW/L). In addition, the safe bending strengths of the wrinkled models are determined.