Abstract: Concerning　the 　dissimilarit y　between　ori ginal 　spatial 　data 　and　pro gressivel y　transmitted 　spatial 　datathis 　paper 　pro poses 　a　model　for　measuring　the 　similarit y　of 　curve 　datasets．After 　curve 　similarit y　is　measured　based　on　differences 　of 　the 　to polo gical 　and　geometric 　characteristicsthe　weighted 　similarit y　and 　the 　simi larit y　precision 　for 　curve　datasets 　are 　computed．The　model　uses　weighted 　similarit y　to 　assess 　the 　overall 　degree 　of 　similarit y　for 　curve　datasets 　and　uses 　similarit y　precision 　to 　assess 　the 　similarit y　differences 　between curves．Finall ythe　model　was　used 　in 　an　experiment 　and　verified 　for 　effectiveness