The invention discloses artificially synthesized gene sequences of mcry1Ba and mcry1Ia with high toxicity to lepidoptera pests and a gene combination, and belongs to the technical field of biological prevention and treatment. According to the two new DNA sequences (shown by SEQ ID NO1 and SEQ ID NO2 in the sequence table) which are artificially optimized, transformed and synthesized by gene Bt cry1Ba and gene Bt cry1Ia which are high in toxicity to the lepidoptera pests, the conversion success rate of the gene Bt cry1Ba and the gene Bt cry1Ia in a transgenosis process is increased by using a codon sequence preferred by plants, and also the expression amount of the genes in transgenic plants and the stable expression characteristic are improved; by the combination application of the two genes, the insecticidal activity of the genes is improved. A new plant expression vector is constructed by using promoters for constitutive expression, so that the conversion rate is high, the expression amount is high and stable, and the artificially synthesized gene sequences can be used for researching the transgenic plants.