It is desirable that massive data of Web maps can be incorporated into desktop GIS systems for use and analysis. But Web maps can not be added into desktop GIS systems directly, because Web maps don’t conform to the geospatial service standard published by OGC. Fortunately, the tile of Web maps can be downloaded and advanced desktop GIS has a built-in extension mechanism. Those together make it possible to integrate desktop GIS applications and Web Maps. This paper presents a generic method for the integration. Most Web maps consist of sets of tiles of multiple scales, covering the entire surface of the Earth at each zoom level. A key of the method is the acquisition of dynamic information of Web maps, such as the extent and zoom level of the right set of tiles and the URL of each tile, from the projection and resolution of Web maps and the extent of the active view in the desktop GIS system. In order to accelerate the process of downloading the tiles and to make it not interfere with other operations of desktop GIS system, the process of tiles downloading should be asynchronous and Multi-Threaded. After fetching the tiles, the tiles may be cached. By tagging spatial reference information to the tiles, the tile images can be turned into raster layers supported by most GIS platforms. The custom layers control the drawing properties and the actual drawing of the set of tiles. Furthermore, different Web maps can be accessed using a uniform interface through the introduced configuration mechanism for dealing with multiple data source. To test and verify the proposed method, we choose ArcGIS Desktop as the test platform. Custom extension and custom toolbar have been employed in the implementation of custom layers. With the developed extension and its associated toolbar, Web maps can be added into and displayed instantly and dynamically in ArcGIS Desktop. Four categories of Web maps are supported, which amount to twelve layers, including Google maps, Bing maps and Esri map services. The advantages and limitations of the method are discussed. The proposed method may find wide applications in other cases of integrating desktop and web applications.