The flower’s meristematic characteristic gene AP1 was introduced into Chrysanthemum morifolium cv. ‘Yu Ren Mian’ mediated by Agrobacterium tumefaciens.The factors influencing genetic transformation protocol were studied.The results showed that the leaf explants precultured for 2~8 hours or not precultured were best for transformation by A. tumefaciens. The suitable concentration of bacterial and the time for infecting was OD_ 600 0.5 for 10 minutes. Leaves were cocultivated with bacterial at 23~25 ℃ for 2 days,then delayed selection for 3 days. Kan^r plant were selected by increased selective press from 5 mg·L ~ -1 G418 to 7.5 mg5L~ -1 G418 followed by 10 mg5L~ -1 G418. The integration of AP1 gene into C. morifolium ‘Yu Ren Mian’ was confirmed by PCR and Southern blotting.Two of transgenic plants bloomed 15 days earlier than untransformed plants.