Abstract: In this paper,a real-time compression algorithm for spatial data was proposed to improve the quality of spatial information service.The algorithm includes two key points.Firstly,the coding rules of RLE were developed.Only if the number of repeated byte reaches to 3or more,the stream segment is allowed to code with the two bytes,one is the repeated number,another is the repeated byte.Otherwise,the stream segment is output directly after the number of uncoded bytes.Secondly,self-adaptive interval run length coding was put forward.The intervals of 24,16and 4are used to test the compression ratio of the origin spatial data stream.The interval of the highest compression ratio is used as the final coding strategy.It was proved that the algorithm of this paper can be used to the spatial data transmission and make real-time transmission of spatial data possible.