Abstract:In order to find out the differences between the fermentation mycelium and the natural mycelium of Paecilomyces hepialid， a comparative study on the composition and content of polysaccharide were analyzed. And the bioactivities of polysaccharides from two kinds of mycelium were compared by MTT assay. There were two polysaccharides in fermentation mycelium， molecular weight of 3 682 000 and 166 000. And there were three polysaccharides in natural mycelium， molecular weight of 400 000， 215 000 and 127 000. The MTT assay showed that both kinds of polysaccharides had promoting effect to the spleen cell proliferation， and the fermen－ tation polysaccharides were slightly better. Both kinds of polysaccharides could reduce the inhibition of tumor supernatant of murine spleen cell proliferation in vitro， and there was no significant difference between two kinds of polysaccharides. The secretion of TGFβ1 of various tumors supernatant， which added polysaccharides， was significantly reduced. Both kinds of could inhibit the growth of tumor cells， and there was no significant dif－ ference between two kinds of polysaccharides. It showed that there were no significant differences between two kinds of polysaccharides in biological activities.