Abstract: In order to study the wave propagation problems under the obstacles environment, we use the domain decomposition principle to solve parabolic equation. In this method, we firstly establish the mathematical model of the parabolic equation, then decompose the domain in the barrier. Next, we calculate the field values of different regions by partition using discrete mixed Fourier transform(DMFT) and finite difference(FD) algorithms respectively. Then, Thomas algorithm is introduced to improve the calculation efficiency and achieve the total field computation quickly in the obstacles environment. Finally, method of moment is used to validate our new method. Simulation results show that two methods have good consistency. The new algorithm has the characteristics of extended applicability and increased computation speed, providing a novel and reliable approach to study the wave propagation problems under the obstacle environment.