In this study, a total of 255 samples ofhard clam and 240 pondwater of farming were collected from Tainan, Chiayi, Yunlin, and Changhua from January 2015 to November 2018. After preliminary analysis of water testing, laboratory microbiology, pathology and molecular biology, the study, tried to established the prevalence rate of disease in cultured clam. Based on the comprehensive diagnosis results, the prevalence of the prevalence of clamswas analyzed, and 129 ( 50.59%) of the poor water quality were the most common, followed by poor water quality and the bacteria infected complex. bacterial mixed infections were 100 samples ( 39.22%), followed by poor water and suspected viral mixed infections in 16 samples ( 6.27%), and ciliated protozoal infections in 10 samples.( 3.92%). When the sulphide concentration was measured by the EPD standard method - the methine blue method and the water quality spectrophotometer method, whether the fresh water and sea water values were subjected to the chloride ion interference test was compared. The results showed that there was no significant difference between the seawater and the fresh water. .The simple reagent developed can produce obvious black precipitate in the laboratory, but the water color applied to the breeding pond only shows milky white and no black precipitate, and whether it is interfered by substances other than chloride ions, further research is needed.