Abstract: The composite wind turbine blade was simplified to a symmetric un-uniform laminate beam for researching its bend-twist coupling effect. The influence of coupling area on bend-twist coupling effect was studied by experiment and numerical analysis method. The ply layouts and manufacturing method of symmetric un-uniform laminated plate beams were presented. The bend-twist coupling test of symmetric un-uniform laminated plate beams was designed, in which the principle and measuring method of the experiment were given. The deflection and twist angle of un-uniform symmetric laminated plate beams were tested in the experiment. The finite element models were established based on ANSYS software and their deformations were got under the concentrated force. Comparing the numerical results with the experimental results, it shows that coupling area has an important influence to deformational behavior of symmetric un-uniform laminated plate beams and coupling in central region can obtain remarkable bend-twist coupling effect.