The leaves of Dianthus chinensis were used to transform ACO gene with Agrobaceriumtumefaciens-mediated system to obtain the new Dianthus with extending flowering period.Results showed that H58Ⅱ，X82I and H68Ⅲ had high differentiation rates of 56.9%,31.7% and 93.2% when the concentrations of BA and NAA in the MS medium were 1.0 mg/L and 0.3 mg/L.The optimal concentration of kanamycin，hygromycin and cephalosporin was 40.0 mg/L，4.0 mg/L and 400.0 mg/L in the selective medium during selective culture of transformation.Transformed leaves and plants presented blue color after being stained.Molecular test showed that the positive rate of transgenic plants was 89%.The vase life for a single flower of plants transformed with ACO gene was 12 days compared with the wild plants flowers of 6 days.The population flowering period of transformed plants in pots was 45 days while that of wild plants was 30 days.