The method of hight performance liquid chromatography(HPLC) was used to analyse the dynamic rule about accumulating β-carotene isomers in Dunaliella salina under the special stress conditions.The results show:1.The strength of stress conditions is advantageous to accumulate trans-isomer, otherwise,decreasing the stress conditions advantage to accumulat cis-isomers. For example, under the conditions of 32℃ with light intensity 10 000 lx, salinity 18%, the amount of trans-isomeris most (2.593 mg/L), but the cis-isomers amount is most (0.630 mg/L) under 25℃, indoornature light and salinity 24%.2.The kind and amount of cis-ismoers are different when the stress conditions are changed.After being cultured 30 days,trans-isomer and two cis-isomers were obtained under 25℃,indoor nature light salinity 24%,but only trans-isomer and one cis-isomer were obtained,when 32℃ with 10 000 lx light intensity and salinity 18%.3.Eventhongh the stress conditions is the same, it is different of the isomers'kind and amount only when culturing time is changed.For example: under the conditions of 25℃ 10 000 lx,18% salinity, only trans-isomer was found before culturing,after 8 days and 19 days,trans-isomer and two cis-isomer, after 34 days,trans-isomer and one cis-isomer were found.