This study is to investigate the optimum time for DNA microinjection via pollen tube pathway and effect of DNA microinjection on the capsule development at different duration after pollination in C. sieboldii Decne. The pollen was found germinated at 48 hours and fertilized at 60 days after pollination. The percentage in capsule set was 100% in the treatment of DNA microinjection at 55 days after pollination, but the highest fresh weight which was 2.6g per capsule was shown in the treatment microinjected at 60 days after pollination. These results indicated that the optimum time for DNA microinjection via pollen tube pathway was at 55 days after pollination.