目的　探讨水淹对钉螺生存的影响 ,为长江洪水和三峡建坝引起的水位变化对血吸虫传播的影响提供依据。方法　应用系统抽样法进行现场查螺 ,现场和实验室模拟水淹实验观察钉螺存活情况。结果　现场查螺显示 ,3- 6月份未淹水洲滩以成螺为主 ,密度基本稳定在 17- 2 3只 /框 (每框为 0 .1m2 )之间 ;7- 9月份洲滩被水淹没 ,启动了钉螺的世代交替 ,新螺急剧上升并生长发育 ,8月份达到最高 80 .95只 /草帘 (0 .1m2 ) ,之后又急剧下降 ,而老螺大量死亡 ,基本稳定在 2 - 5只 /草帘 ;退水后的洲滩以新螺为主 ,其密度是淹水前洲滩的 6 .0 6倍。现场模拟钉螺水淹实验显示 ,淹水 1个月钉螺存活率急剧下降 ,之后则稳定在 5 .8% - 8.7%之间 ;实验室模拟淹水显示 ,不管是在夏季还是冬季 ,淹水使得钉螺存活率下降 ,以夏季更为明显 ,并随着淹水时间的延长而继续下降 ,而与淹水的深度无关。结论　淹水可促进幼螺的生长发育和成螺的死亡 ,自然淹水成倍增加洲滩的活螺密度 ,并且有小部分成螺仍能在一个自然淹水期存活 Objective To investigate the effect of flooding on the survival of Oncomelania snails, and to provide basis for the influence of the water level changes caused by the Three Gorges Dam on the spread of schistosomiasis. Methods Systematic sampling method was used to check snails on site, and live and laboratory simulation flooding experiments were used to observe snail survival. The results showed that snakeheads were not flooded in 3-6 month and the density was basically stable between 17-223 per box (0.1m2 per box) Inundation of water started the generations of snails spiraling. The snails rose sharply and grew and reached a peak of 80.95 pieces / straw curtain (0.lm2) in August and dropped sharply thereafter, while the large number of old snails died, basically stable at 2 - 5 / straw curtains; the rehabilitated Chau Beach is dominated by snail, its density is 6.60 times that of the beach before flood. In-situ simulated snail flooding experiments showed that the survival rate of snails at 1 month after flooding dropped sharply, and then stabilized at between 5.8% and 8.7%. Laboratory simulated flooding showed that in summer or winter flooded The survival rate of snails decreased, which was more obvious in summer and continued to decline with the extension of flooding time, but not related to the depth of flooding. Conclusions Flooding can promote the growth and snail death of young snails, naturally flooding to multiply the live lobe density in Juban Beach, and a small number of snails still survive in a natural flooding period