Objective To analyze the characteristics and changes of Oncomdania snail distribution in regions with different epidemic types and degrees of Jiangsu Province,so as to provide the evidence for implementing the feasible schistosomiasis control strategy.Methods A retrespeetive survey was performed,and the 5-year database of snail status in Jiangsu Province was established based on the collected reports of snail habitat cards and schistosomiasis control in Jiangsu Province from 2004 to 2008.The changes of snail areas,infected snail aroas,infection rates of snails in different years were analyzed,and tIIe annual vailations of snail areas,infected snail areas and infection rates of snails in areas with different epidemic types and degrees were eomparedI Results The actual snail areas and infected snail areas decreased by 3 799.86 hm~2 and 2 006.35 hm~2.respectively in Jiangsu Province.2006-2008.with the annual meaan decreasing rates of 9.64% and 18.83%.Among them,the actual snail areas in marshland and lake regions,water net regions and mountainous regions decreased by 3 546.10.209.19 hm~2 and 44.57 hm~2,respectively,with the annual meall decreasing rates of 9.59%,10.29% and 11.18%,respectively.An area of 22.02 hm~2 of new snail habitatswas detected during the 5 years,and thewater net regions accounted for 89.24%.Theproportions of actual snail areas in historical snail ale,as were between 2.77% and 5.36%.Among them.the proportions of actual snail areas in historical accumulative snail area8 in transmission-uncontrolled.trailsmission-controlled and transmission-interrupted areas were 13.29%-22.82%,0.88%-3.54% and 0.14%-0.32%,respectively,and there were significant differences among them(P<0.01).The constituent ratios of the actual snail areaswere 93.79%-95.60%.3.67%-5.45% and 0.73%-1.01%, respectively in marshland and lake regions,water net regions and mountainous regions from 2004 to 2008.The infection rate of snails in Jiangsu Province reduced from 0.15% in 2004 to 0.02% in 2008,with a reduction rate of 85.50%(P<0.01).The constituent ratios of infected snail areas in transmission-uncontrolled, transmission-controlled and transmission-interrupted areas were 98.15%-100%,0-0.81%, and 0-1.43%,respectively.Conclusions As a whole,there is a decreasing tendency of snail areas and infected snail areas in Jiangsu Province.and the snail control has been consohdated step by step in transmission-interrupted areas.The effective control of snails in marshland and lake regions and infected snails in transmission-uncontrolled areas are the key points in the future schistosomiasis control of Jiangsu Province.