Radar and microwave non-destructive testing (NDT) technique is used to simulate a concrete-filled Fiber Reinforced Polymer (FRP) tubes and a concrete pile containing defects (delamination, crack, void). The delamination that occurs as a result of external factors is modeled as closest to the reality. Interaction of electromagnetic wave and the concrete pile is utilized for numerical simulation. A Finite-Difference Time-Domain (FDTD) method with Perfectly Matched Layer (PML) Absorbing Boundary Condition (ABC) is proposed to simulate electromagnetic wave propagation in FRP tube and composite pile. 2D simulation of a wave generated from a point source at microwave frequencies is obtained by using MATLAB (R).