Collect the coast water of Yunlin and Chiayi county for water quality and heavy metal analysis. Water Temperature between 17.6-32.1℃ , p H between 8.03-8.41, Salinity between 26-37ppt, dissolve oxygen between 5.0-8.3 mg/l, SS between 12.5-125 mg/l, COD between 0.2-4.6ppm, ammonia-N between 0.1-1037.4ppb, nitrite between 1.1-19.8ppb, nitrate between 2.6-206.1ppb. Cu+2 ion between 0-73ppb, Zn+2 ion between 0-390 ppb. Redox potential in the bottom soil decreased with the rearing time. Clam’s body weight has a positive relationship with redox potential, R=0.647. Regression of body weight and redox potential have significant difference (P<0.01).