In order to solve the problems of low detection accuracy and poor modelling effect when building the laminated defect aluminium beam model, a 3D finite element simulation model of laminated defect aluminium beam based on 2D Fourier transform is proposed. The two-dimensional Fourier transform method was used to obtain the full wave field signal and spatial position wave number curve of aluminium beam structure. The three-dimensional point cloud image was generated by MATLAB software, and the solid model of aluminium beam with delamination defect was established. The three-dimensional finite element simulation model of aluminium beam with laminated defects was obtained by introducing it into the worktable. The experimental results show that the accuracy of the method is 98.91%, the average texture number and frame rate are 17.105 ms and 95.507 frames/second, respectively. It has a good effect on the establishment of 3D finite element simulation model of aluminium beam.