In this article, we use digital watermark technology and file filter drive technology to insert the file filter encryption drive layer between the file system drive layer and the application layer, using the fragile digital watermarking technology in this layer, we can detect the integrity of DEM spatial data files, using the robust digital watermarking technology, we can detect whether the data files are protected files. Experiments prove that this model has strong abilities in protecting the integrity of files, preventing the illegal spread of protected files and so on.