B. thuringiensis strain C005 with high insecticidal activity to several kinds of pests, screened from China, was identified that it contained cry1Ab gene by PCR-RFLP. Southern blotting showed that a 8.5 kb positive band of plasmid DNA digested with PstI contained cry1Ab gene. The gene was cloned from Bt C005 and the results of sequence analysis showed that cry1Ab13 gene contained a 3468 bp open reading frame, encoding a 130.6 kD protein composing 1155 amino acids. The IE point of Cry1Ab13 protein was pH 4.845. The cry1Ab gene has been registered in GenBank (Accession number is AF254640) and named as cry1Ab13 as a novel gene by International Nomenclature Committee of Bt delta-endotoxin genes. SDS-PAGE analysis indicated that 130 kD protein of Cry1Ab13 was expressed in a Bt acrystalliferous mutant cryB- and bioassay results proved that the transformant BiotI81 containing cry1Ab13 gene had high toxicity to Plutella xylostella.