Catering to the request of real-time characteristic of LBS, progressive transmission method of vector map data based wireless net is researched in this paper, in which the great data capacity of vector map and the narrow bandwidth of wireless network are considered as well. In the method, firstly, the map data needing to be transmitted are pre-processed. Different scales vector map data are depicted by LOD model and stored by multiple scale database (MSDB) in the server. Then according to the request of client, the requested scale vector map is dynamically retrieved. Finally the map data are gradually transmitted to client through the data increasable method and are combined in client. In the whole transmission process, responding to client's request, the transmission process begins with a low resolution vector data, with the transmission process going on, the resolution of the data arrived to client is progressively improved. The architecture of the transmission system is analyzed, data pre-processing and store method being studied and the whole transmission process of vector map data is expounded.