<正>Objective: To explore the spatial distribution of oncomelenia snails in Jiangning County. Methods: Cluster analysis and the Spatial Scan Statistics were performed based on the density of alive-snails in habitats and its rate infected by the 5. japonicum. Results : Although areas of snail habitats and density of the alive-snails in marshland in 2000 are higher significantly than that in mountain areas in Jiangning County

the numbers of habitats in mountain are more than that in marshland and they distributed sporadically. The snail habitats were classified into 4 in marshlands and 3 classes in mountain areas respectively in cluster analysis. Although they are mainly the one with low density of alive and infected snails

we should alert that there are also some habitats with high snail density and infection rate

which is important for the transmission of schis-tosomia. The analysis of Spatial Scan Statistics detected 2 significant spatial aggregations for alive-snail in marshland and 4 in mountain areas