Genetic improvement in cotton via biotechnology is limited due to lack of an efficient transformation and regeneration system.A reliable and high-efficiency system of genetic transformation mediated by Agrobacterium tumefaciens was developed in cotton(Gossypium hirsutum L.)cultivarXinluzao 33(an elite cultivar in Xinjiang area),using hypocotyl as explants.Various aspects of transformation were examined in efforts to improve the efficiency of producing transgenic plants.Meanwhile,a foreign gene Polyga-lacturonase-inhibiting protein(AtPGIP1),which is related to plant disease resistance,was induced to this cultivar.The integration of the interest gene and BAR transgenes into the genome of putative transgenic plants was confirmed by polymerase chain reaction(PCR).Our results showed Basta is an effective selection agent in cotton genetic transformation,which can be applied at a low concentration of 2.5mg/L. Agrobacteriumat a relatively low concentration(OD_(600)=0.5)helped to improve the efficiency of transformation. Relatively low co-cultivation temperature(20℃)was optimal for obtaining a higher efficient transformation. This result suggested thatXinluzao 33can be used as a good receptor variety in cotton genetic transformation mediated by A.tumefaciens,increasing the range of cotton genotypes that can be transformed. Using this protocol,more than 15normal plants were obtained through transformation of AtPGIP1, of which all regenerated plants were transgene-positive confirmed by PCR analysis.The protocol established in this study can be used in cotton functional genomics and in improving cotton cultivars by genetic engineering.