In this study, a forest stand was assembled according to the results from forest growth model. The L-system was used to generate the realistic geometry of trees. The 3D model of the assembled forest stand then was used as input to 3D radar backscatter model. As the first step, larch forest stands at ages of 10, 30 and 80 years, that correspond to the young, mid-age, and mature forests commonly used in forest management practice in Northeastern China, were simulated. The simulation results were compared with SAR images