Buffer analysis is a very important spatial function of Geographic Information System（ GIS）. However

its efficiency in terms of time and space when used to process massive amounts of geographic data is very limited. To solve this problem

we define an approximate representation form—equational buffer which uses a mathematical equation to simulate the boundary of a buffer in GIS. Using equational buffer

buffer analysis is converted from a process composed of complicated geometric calculations to a process composed of simple algebraic calculations

leading to increased computational efficiency. This paper introduces the definition

pattern

application method and performance of the equational buffer. We also apply the equational buffer in the process of d ata filtering when estimating the real-time traffic information of China’s highways based on floating car data

and the experiment result validates that equational buffers are highly efficient in processing massive amounts of geographic data.