Abstract: The culture medium of Xenorhabdus nematophila var. pekingensis was improved based on tests of nutrition requirements. The result showed that fructose, glutamic acid and phosphate increased insecticidal activity. The optimum culture media was (g/L): soybean flour 40, sucrose 15, peptone 15, yeast extract 10, maize slurry 5.0, sodium chloride 5.0, phosphate 1.0, glutamic acid 5.0. The fermentation filtrate of X. nematophila var. pekingensis cultured in optimum medium displayed insecticidal activity. Rate of growth inhibition of neonate larvae of Ostrinia furnacalis was 90.81%. It was increased by 46.5% in comparison with basic culture medium (TSB).