The study was to investigated the gene expression of light harvesting complex II (LhcII) of photosystem II (PSII) and Photosystem I reaction center subunit III (psaF) in the marine macroalga Ulva fasciata Delile in relation to copper (50 £gM CuSO4) and hypersalinity (90‰ ASW) stress. Excess copper had little effect on photosynthetic ability and gene expression of LhcII and psaF. Hypersaline decreased Fv/Fm and Fv'/Fm', but increased LhcII and psaF transcript level to a plateau after 6 h. The effects of ROS scavengers(5 mM dimethylthiourea (DMTU)¡B10 mM 4,5-dihydroxy-1,3-benzenedisulfonic acid (Tiron) or 10 mM sodium benzoate (SB) to 90‰-grown thalli) on LhcII and psaF gene expression were examined by exogenous application of. Indicate that O2•¡Ð is the factor for mediating LhcII gene expression by 90‰ while O2•¡Ð¡BH2O2 and OH• are related to the induction of psaF gene expression by hypersalinity. Exogenously applied spermidine (Spd) and spermine (Spm) recovered Fv/Fm and Fv'/Fm' and decreased LhcII and psaF transcript levels by 90‰ while putrescine (Put) recovered only Fv'/Fm' but not effect on Fv/Fm and LhcII transcript levels were increased. Electron-transport inhibitors, 50 £gM 3-(3,4 dichlorophenyl) -1,1-dimethyl urea (DCMU) or 50 £gM 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB) , applied to the 30‰-grown thalli decreased Fv/Fm and Fv'/Fm' but increased LhcII transcript levels while psaF transcript levels were decreased.It could be concluded that the expression of LhcII and psaF were influenced by the redox state of plastoquinone pool (PQ pool) and photosynthetic electron flow ; Reactive oxygen species produced under hypersaline condition influenced the LhcII and psaF transcript level, and polyamine might play a protective role against salt stress by the modulation of LhcII and psaF gene expression.