A senescence-related gene LoENDONUCLEASE 1 （SAG10） was cloned from the tepals of Lilium oriental hybrid ‘Siberia’ to study the molecular mechanism underlying the senescence of flower in lily （Lilium spp.）. The expression of SAG10 was analyzed with qRT-PCR， and the function of LoENDONUCLEASE 1 gene was identified with Agrobacterium-mediated stable overexpression system of Arabidopsis thaliana and transient overexpression system of lily tepals. The results showed that the open reading frame （ORF） of LoENDONUCLEASE 1 gene was 921 bp， encoding 306 amino acids. LoENDONUCLEASE 1 was uniquely expressed in the senescence of flowers and leaves in lily， and was induced by abscisic acid and salicylic acid. The content of chlorophyll in leaves of Arabidopsis strain with overexpressing LoENDONUCLEASE 1 was significantly lower than that in the control. LoENDONUCLEASE 1 gene was transiently overexpressed in lily tepals， accelerating the senescence of tepals in lily. The content of malondialdehyde （MDA） and ion leakage rate in the overexpressed tepals were significantly higher than that in the control. It is indicated that LoENDONUCLEASE 1 can promote the senescence of flowers and leaves in lily.