Abstract: In this research,the differences between wild-type Arabidopsis thaliana and the AtDAD1 overexpression type in their tolerance to high dosages of H₂O₂ were compared.The diversity on their phenotype from the germination to ripeness was also observed.The results demonstrated that the overexpression of AtDAD1 conferred the transgenic plant more resistant to H₂O₂ stress.It is also be found that the sugar content in leaves of transgenic plant is much higher than that in wild-type Arabidopsis leaves.Since many lines of evidence have proved that H₂O₂ is a factor leading to programmed cell death (PCD) and sugar is important for leaf senescence and cell death,it was inferred that AtDAD1 maybe have some effect on Arabidopsis resistance to PCD.