We mainly focused on optical remote sensing. We know that optical remote sensing images have been widely used for land cover classification. We noticed that some researchers conducted their study using Sentinel-1 SAR (Synthetic Aperture Radar) images. Even though optical remote sensing data are often contaminated by cloud and thus no many data can be used. However, most land cover types do not changed within short time. Then, when can we choose Sentinel-1 data used for classification topics? In what case, it is helpful and feasible to use it for classification ?