Abstract: Three pCO₂ levels of 380 ppm、750 ppm and 1900 ppm(effective pH being 8.06、7.72 and 7.41, respectively)were set to observe the effects of ocean acidification driven by excessive CO₂ on the carbon and nitrogen budgets in sea cucumber Apostichopus japonicus (Selenka), which is an ecologically and economically important holothurians in East Asia.Results showed that seawater acidification inhibited ingested carbon and nitrogen in A.japonicus, with 40.28 mg/g/d carbon and 2.48 mg/g/d nitrogen decreased while pH fell by 1 unit.The impact of pH on carbon and nitrogen budgets were variable:the feces carbon/nitrogen, respiration carbon and excretion nitrogen linearly decreased with decreased pH whereas growth carbon/nitrogen did not.The ocean acidification affected the allocation models of carbon and nitrogen budgets, but the proportion of growth carbon/nitrogen in digested carbon/nitrogen was not affected statistically.These findings indicated that A.japonicus is resilient to ocean acidification, which would be due to its less-calcified feature and the "pre-adaptation" in variable pH environment.