Control of aflatoxin contamination has been a worldwide problem. Laminarin from Laminaria digitata is one kind of polysaccharides with multiple biological activities. In this paper, the inhibitory effects of Laminarin on the growth and toxin production of A. flavus was studied. The results indicated that 150 and 200 µg/mL of Laminarin ccould significantly inhibit the aflatoxin production in Sabouraud liquid medium (Sab), without affecting mycelium growth. In addition, the results also showed that certain concentration Laminaria could decrease the infection of peanut seeds by A. flavus as well as the contamination by aflatoxin B1.