Lily ( Lilium longiflorum L.) from the Liliaceae family is one of the most important cut flowers and commercially cultivated as bed flower around the world in recent years. In the process of lily flower production, flower quality has special importance including flower color, flower size (tepal length) flower number, stem diameter and length and postharvest life respectively. In the present study, the effect of nitric oxide application in the form of sodium nitroprusside, was evaluated on the qualitative characteristics (morphological and physiological characteristics) of lilium cut flowers "Teresor" in Isfahan University of Technology. In the first experiment after the establishment and formation of the first buds, plants were sprayed with sodium nitroprusside (nitric oxide-releasing compound) at concentrations of 0, 50, 100, 200, 500 µM. The experiment was conducted based on a randomized complete block with 5 treatments an 4 replicates and each replicate contained 3 pot. In the second experiment, lilium flowers of the first test (5 concentrations of sodium nitroprusside) were harvested at stage of get color of the first buds and in order to 5 treatment were treated with 200 µM sodium nitroprusside 24 hours. 8-Hydroxyquinoline sulfate (200 mg/l), amino-oxy-acetic acid (0.5 mM) and distilled water was used as a control for 24 hours. The second experiment was conducted with 8 treatments and 3 replicates and each replicate contained 3 cut flowers. The results of the first tests showed that 200 µM sodium nitroprusside before harvesting had the greatest impact on the stem diameter and reducing ACC oxidase activity. Maximum chlorophyll content and the lowest electrolyte leakage amount was related to 100 µM sodium nitroprusside treatment. The carotenoids and anthocyanins contents reached the peak in 500 µM sodium nitroprusside. Based on the results of the second experiment 0 µM sodium nitroprusside increased flower diameter. The greatest relative water content was related to the treatment 50 µM sodium nitroprusside. 0.5 mmol aminooxyaceticacid reduced electrolyte leakage up to 56.96% more than the control treatment. However there was no significant difference with 100 µM sodium nitroprusside. The maximum vase life, total chlorophyll and carotenoid contents and the lowest ACC oxidase activity was observed in 100 µM sodium nitroprusside; The vase life increased 5 days than the control group. The result showed that the application of nitroprusside sodium can be successfully employed to increases postharvest quality of lilium flowers. Keywords: Lilium, Nitric oxide, amino-oxy-acetic acid, 8-Hydroxyquinoline sulfate, ACC oxidase activity, Vase life.