Porphyra dentata is one of the main species of natural resources of Porphyra,which has high economic and medicinal value.It is meaningful to develop and increase new Porphyra cultivation by studying the ecological characteristics of P.dentate.In order to understand physiological responses of P.dentate cultured in different conditions,we studied the responses of P.dentate to different temperature,salinity and light intensity by determining the change about growth,photosynthetic pigments contents,soluble protein contents,malondialdehyde(MDA)contents and the peroxidase activity.The experimental results showed that,thallus was able to maintain a high relatively growth rate under 17-20 ℃,when temperature was higher than 23 ℃,the growth of thallus was inhibited,it turned to redness and appeared to fester.At salinity of 25-35,the thallus grew quickly under culture conditions,when culture salinity was lower than 25,the content of photosynthetic pigment,soluble protein,malondialdehyde(MDA)and the activity of peroxidase(POD)and catalase(CAT)of thallus was significantly changed,and thallus became thinner and whitish,its edge displayed decay phenomenon.The thallus had a high growth rate under culture light intensity of 3 000- 6 000 lx ,when the culture light intensity reached 9 000 lx,content of chlorophyll a of thallus was low,but the content of soluble protein and MDA and the activity of POD were significantly increased,the thallus began to fester after several days’ culture.According to the result,we know that suitable culture conditions for P.dentata thallus are temperature of 17-20 ℃,salinity of 25-35,and light intensity of 6 000 lx.