A regulation of calcium ion on jerusalem artichoke(JA) seedlings under seawater salt(SWS) and NaCl with the same salt content was made with three calcium ion concentration of 5 mmol/L,10 mmol/L and 20 mmol/L.The effects of calcium ion on biomass,SOD activity,MDA content,relative conductivity,chlorophyll content and net photosynthetic were studied.The results indicated that: normal metabolism of JA was markedly inhibited by 1.0% SWS and 1.0% NaCl.However,addition of Ca~(2 ) could alleviate the effects of SWS and NaCl stresses on JA in different degree,so higher biomass,SOD activity,chlorophyll content and net photosynthetic rate,lower content of MDA and relative conductivity were maintained,especially 10 mmol/L Ca~(2 ).Above 10 mmol/L the alleviation decreased.As a result,appropriate concentration Ca~(2 ) could significantly protected JA from oxidative damage caused by SWS and NaCl stresses.Therefore,higher SOD activity,chlorophyll content and net photosynthetic rate,lower content of MDA and relative conductivity were maintained.These were propitious to the dry matter accumulation so that the fresh weight was increased significantly.At Ca~(2 ) concentration of 5 mmol/L,10 mmol/L the effect of Ca~(2 ) on alleviation of SWS stress was superior to NaCl stress significantly,whereas the two treatments did not have pronounced difference when the concentration was 20 mmol/L.