Abstract: In order to study the effects and mechanism of aquatic cadmium on aquaculture,some metabolic change was researched when the holothuria were exposed to cadmium chloride solution with different concentration and subjected to certain days respectively.The results indicate that,under the conditions of increased cadmium exposure,the SOD activity was enhanced,but both LDH activity and AKP activity reduced,and MDA contents rose in the coelomic fluid and body of holothuria,and the SOD activity was greatly induced by 0.5\mathrmmg/\mathrmL cadmium treatment.The SOD,LDH and AKP activity in the coelomic fluid declined more apparently after holothuria were continuously exposed to cadmium solution,and also AKP activity showed continuous change most obviously.Therefore,AKP is the best enzyme for estimating the toxicological effect of holothuria polluted by cadmium chloride,and holothuria can be regulated by antagonism as the cadmium concentration is lower to 0.5\mathrmmg/\mathrmL.