Abstract: A fast method in polarimetric Synthetic Aperture Radar (SAR) data simulation for three-dimension forest application is proposed and the difficult application of SAR echo generation process in wide range and high density forest stand is solved. The method is based on the equivalent scattering process consisting of a few virtual scatters specially obtained by segmenting the entire forest stand into slices, blocks, and pieces. The received signal responded by a cluster of real scatters can be equivalent to that responded by a single virtual scatter in the case of the tiny slant range error. Then, the number of scatterers can be reduced and the efficiency of echo generation process can be improved. The error sensitivity of the equivalent parameters is analyzed and optimum combination of the parameters considering both precision and efficiency is obtained. The experimental results on 2.5105 m2 broadleaf forest stand show that the proposed method provides high efficiency simulation while keeping high precision on both echoes and images. The forest height inversion results on 1.0106 m2 broadleaf forest stand demonstrate the feasibility and potential utilities of the proposed method for large area forest applications.