Twenty-six strains of Aspergillus fumigatus were screened for toxigenicity for fumitremorgins A and B. Twenty-three of 26 strains can produce fumitremorgin B in rice medium determined by TLC and HPLC, and no fumitremorgin A was detected. The strains of no. C4104 and no. 3656 were inoculated onto 5 kg of rice media and incubated in a modified procedure. Finally, 4.0 g of fumitremorgin B was obtained after extraction and purification by modified methods, and was confirmed by TLC, HPLC, spectral analysis together with other physicochemical analysis. This is the first report of the preparation of fumitremorgin B in China.