In order to screen new microbial strains with high degrading capabilities for beta-cypermethrin from agri-cultural by-products, five strains were isolated from the activated sludge. By liquid chromatography analysis, astrain named XCH-5 exhibited the strongest degradation ability among these five strains. Further investigation re-vealed that XCH-5 was Aspergillus terricola as showed by morphological characteristics and ITS sequencing analy-sis. By orthogonal design method, the optimal combinations of the strain XCH-5 for beta-cypermethrin degradationwere found with inoculation amount of 0.2 g/L, temperature 35℃, and p H 7.5. Under the optimized conditions,XCH-5 showed 78% of degradation rate for beta-cypermethrin after ten days of treatment.