Fatty acyl desaturase (Fad) is the crucial enzyme for biosynthesis of long chain polyunsaturated fatty acid (LCPUFA) from C18 polyunsaturated fatty acid (PUFA). The molecular mechanism of dietary fatty acid regulate the gene expression of fatty acyl desaturase (Fad) in aquatic animal is still not clear. Using the technologies of modern nutriology, biochemistry and molecular biology, this project will be conducted to study the regulation of sterol regulatory element binding proteins 1 (SREBP-1) and peroxisome proliferator-activated receptors α (PPARα) on the Δ5 Fad promoter of abalone (Haliotis discus hannai Ino), investigate the effect of dietary fatty acids on gene expression of Δ5 Fad, SREBP-1 and PPARα and consequently illuminate the involvement of SREBP-1 and PPARα in the regulation of abalone Δ5 Fad by dietary fatty acid. This study not only fill the gap in this research field but also provide theoretical basis for improving the capability of abalone to biosynthesize LCPUFA from C18 precursors.