The invention relates to a bacillus thuringiensis FH21, an insecticide gene, an expression protein and an application thereof, and belongs to the technical field of biological control. The collection number of the bacillus thuringiensis FH21strain is CGMCC No.10090, four insecticide proteins are separated out from the strain, the strain has the amino acid sequences represented by SEQ IN No 2, 4, 6, 8, and gene for encoding the insecticide proteins, preferably, the nucleotide sequences of the gene are represented by SEQ ID No 1, 3, 5, 7. The strain and the gene have high toxicity to lepidoptera pests, is applicable for converted microorganisms and plants to show the toxicity to related pests, and the resistance to drugs of the pests to engineering bacteria and transgenic plants are overcome and delayed.