The cowpea trypsin inhibitor (CpTI) gene was transferred into the cotyledons and hypocotyls of cauliflower mediated by Agrobacterium tumefaciens. In the selective medium, the kanamycin concentration was 15 mg/L. Carbencillin (500 mg/L) was used to inhibit growth of agrobacterium. The regenerated transformant plants were assayed by PCR, PCR-Southern blot and Southern blot, and the target band was observed in most of the plants assayed. So the integration of the CpTI gene into cauliflower genome DNA was confirmed. In vitro leaf testing for evaluating resistance to cabbage worm (Pieris brassicae L.) was made, and the results showed that the transgenic plants were more resistant than non-transgenic plants.