Abstract: In dam-circle marsh region,the authors examined nearly one thousand residents by Kato-Katzcs method,hatching method,IHA and Ultrasound to learn the prevalence of schistosomiasis and also survey the snail density in that area. Result showed that the positive snail density was 0.099 per 0.11m². Positive rate of fecal examination and IHA was 44.76% and 62.52%. The liver and spleen abnormalities caused by schistosomiasis were also very serious. It shows that much attention should be paid to control the morbidity of dam-circle marsh region because of its unique epidemic environment. It also shows that there is no familial aggregation of schistosomiasis in that area. Much more patients can be checked out if Kato-Katz and hatching methods are used together. IHA can only be used to diagnose as an auxiliary met hod. The standards of liver and spleen abnormalities diagnosed by bultrasound should be improved.