The lectin DDFL from the fruiting bodies of Dityophora duplicata(Bosc) Fischer was isolated and purified by physiological saline extraction, (NH 4) 2SO 4 precipitation and DEAE Sepharose, Sephadex G 100 chromatography purification. It turned out to be a single band on PAGE. The relative molecular mass of DDFL was 45.3 kD tested by gel filtration,and the subunit was 22 3 kD determined by SDS PAGE, its pI was about 3 92 by isoelectrio focusing. This lectin could agglutinate erythrocytes from rabbit, calf, duck, chicken, crucian, frog and 4 types of human erythrocytes, but did not agglutinate erythrocytes from turtle. It also agglutinated the peripheral lymphocytes cells and S 180 tumor cells from mouse. The hemagglutination on rabbit erythrocytes was inhibited by lactose, raffinose,galactose,�� methyl galactose,�� methyl galactose and N acetyl galactosamine. The amino acid composition analysis showed that it contained 17 kinds of amino acid, in which the contents of aspartic acid, serine, phenylalanine and alanine were relatively high. The N terminal of DDFL was glycine. DDFL had certain thermal stable, acid stable and alkali stable, it still had high activity after being heated 10 minutes in 60��, and had high activity within pH 4 0��9 0. Its activity was depended on Mg 2+ and Ca 2+ , not on Mn 2+ and Zn 2+ . DDFL was toxic to mouse by celiac injection with a LD 50 of 70 63 mg/kg.