It is important to solve the low performance of spatial vector data transmission in the client side Intermet GIS （Geographic Information System） which handles large size spatial geographic information on the Internet. This paper has proposed a new efficient method for it. The basic idea is that

firstly

a large size vector map is divided into several parts

where each part is called a ‘Tile’

according to an appropriate division granularity. Secondly

when an user requires a certain region in the map at client side

the GIS server only transmits spatial data in the tiles which overlap with the requested region. And the received data are stored in client local machine for reuse. For the support of this idea

a method of tile division

an algorithm for tile query processing and a strategy for efficient spatial data transmission between server side and client side have been provided. Comparing with the traditional methods of client side Internet GIS

the performance improvement is achieved by the usage of the proposed method.