The study simulated microwave backscattering from all components of forests using MIMICS（Michigan Microwave Canopy Scattering）Model and RADARSAT SAR data, including crown ,trunk and soil layer. The study concluded that, in sparse plantation forest area, the backscattering from direct crown and direct soil are both the most significant factors, and in the same premise, the consistence between the simulated data and the measured data of broadleaf forest was much better than that of conifer forest. For conifer forest, it was largely influenced by rugged terrain and it was difficult to simulate its microwave backscattering. Meanwhile, It was found that by using the forest closure parameter, the relationship between total and direct crown layer forest microwave backscattering could be determined and direct crown layer microwave backscattering could be quantitatively obtained. In the end, the paper validated the method.