Abstract: To keep land use information, the method of land use changing based“3S”technology was discussed in the paper. First, the remote sensing image was dealt with and classified. Then the land use map was overlapped on DOM and classified image to find the changed information. The information change was investigated on the spot, then it was imported to GIS and the land use information was updated finally. Using “3S”technology to update land use is possible. The key questions were discussed and the conclusion was drawn as: land use updating is a systemic project, surveying and precision of image and estimation is important.