By means of comparing biomasses of biodegradation fungi, Fusarium sp. HG-P-01 for β-cypermethrin, a synthetic pyrethroid insecticide used widely in China, in five different media, the Czapek-Dox medium was selected as the best medium for mycelia growth. Furthermore, an experiment of central composite rotatable design (CCRD) was used to optimize the content of nutrient components. The optimal composition of C, N and P in media for HG-P-01 were 20.94 g/L, 1.82 g/L and 1.66 g/L, respectively, in which an expectant or real rate of β-cypermethrin-degradation got to 96.34% or 93.78% by HPLC for a concentration of 50 mg/L after 24 h treatment. The predicted value in degradation rate model was consistent with that from HPLC method.