Karst mountain area is a special and fragile ecological landscape in the southwestern China.Forest optical remote sensing data in the regeion is not easy to obtain timely due to cloudy and rainy weather,affecting the investigation of forest resources in the ecosystem.Synthetic aperture radar (SAR)estimation technology is very suitable for quantitative evaluation of forest volume in cloudy mountain area,because radar has the ability to penetrate clouds onto the canopy,and its microwave can interact with the coronet and branches,resulting in all-weather observation of the forest.In this study,we selected Huishui county karst mountain area in Guizhou Province as the experimental area,and established a parameter model to estimate the forest reserves in the area by using SAR data and the ground data.We further analyzed the accuracy of the estimation from the model and expect that SAR remote sensing technology could facilitate more efficient management of the forest resources and the sustainable development of Guizhou Karst mountain ecosystem。