People have accumulated a large number of 3D landscape data during the construction of digital city. 3D landscape application becomes "island of information" because of the difference of its standard criteria and technical route. Aiming at the public demand of 3D landscape online sharing, the standard of 3D landscape data's content and organization and sharing requirements were analyzed. Second, the research on the network sharing technique was conducted through comparing the sharing and integration mechanism between 2D and 3D geographic data. At last, the ideas and technical route of trans-regional 3D landscape online sharing based on decomposition and combination method were presented. This approach decomposed 3D information into various components such as terrain, image, model, etc. It used standard geographic information service and implemented construction and visualization of 3D information with HTML5 on the client. The simulation results demonstrate that this proposed method can effectively restructure 3D landscape model, and realize resource sharing among province, city and county with a little change.