Abstract: Based on the classical lamination theory (CLT), a multi-parameter analytic model was developed to quantitatively investigate influence of out-of-plane waviness defect on the elastic properties (i.e. elastic modulus, shear modulus and Poisson's ratios) of composite laminates with waviness. The results show that out-of-plane waviness has strong effects on the major elastic modulus, Z-direction elastic modulus, shear modulus in X-Z plane, and in-plane Poisson's ratio. The negative in-plane Poisson's ratio occurs in a particular range of the waviness ratio and wavy region for the example of carbon fiber/epoxy resin material system. The present approach provides a useful reference to evaluate the effects of out-of-plane waviness on elastic properties of composite laminates.