Abstract: Agrobacterium mediated transgenic insect-resistant gene test is conducted in order to select new island cotton lines (varieties) with excellent insect resistance. On the basis of embryonic regeneration system of island cotton somatic cells, the expression vector pBI121 with Cry1A gene was transferred to the embryogenic callus of‘Xinhai 33’by Agrobacterium-mediated method. The insect-resistant offspring were screened by the culture medium screening, PCR detection, RT-PCR detection and insect-resistance identification. 12 resistant plants were obtained. The PCR result revealed that the 12 resistant plants could amplify the expected-size DNA fragments, and the test results were positive. RT- PCR result showed that the target gene had been integrated into 12 transgenic plant genomes, and could reverse transcription of mRNA. The test result of Bt- Cry1Ab/Ac transgenic paper indicated that the 12 transgenic plants contained the target protein. Transgenic plants had certain resistance to cotton bollworm larvae by insect- resistant identification. This study successfully transforms insect-resistant genes into island cotton, obtains the insect-resistant plants, and the results have some reference value for the breeding of new transgenic insect-resistant island cotton varieties.