Salicylic acid (SA) is considered to be plant signal molecule that plays a key role in plant growth, development, and defense responses. The physiological mechanism of exogenous SA to affect the senescence of cut lisianthus flowers during vase life was investigated. Fresh cut lisianthus flowers were treated with distilled water (control), 0.5, 1 and 2 mM SA and then held at 25◦C up to 12 days. Exogenous SA supply at 1 mM extended vase life, which was associated with reduced electrolyte leakage and MDA content.SA treatment also reduced activity of lipoxygenase (LOX), which is responsible for membrane lipid peroxidation. SA treatment also enhanced activities of catalase (CAT) and ascorbate peroxidase (APX) and decreased H2O2 accumulation during vase life. Thus, exogenous SA supply could maintain membrane integrity by increasing antioxidant system activity, thereby retarding the senescence of cut lisianthus flower during vase life.