Insect pests cause the destruction of 20–30% of the world’s crops annually (Estruch et al., 1996). GM crops are becoming an increasingly important feature of agricultural landscapes. As one of the most widely grown GM crops worldwide (James, 2004), Bacillus thuringiensis (Bt) corns were genetically modified by introducing the Bt gene since 1987 to combat the crop damage. The Cry1ab/ac gene in this study originates from the cry1ab gene (GenBank Accession No. X54939) and the cry1ac gene (GenBank Accession No. Y09787) and its encoded Cry1Ab/Ac protein is high toxic to Lepidopteran pests such as Chilo suppressalis, Scirpophaga incertulas, Cnaphalocrocis medinalis.