‘Xuxiang’ kiwifruit were pretreated with 1.0 mmol·L^-1 salicylic acid (SA) and then weight loss, firmness, polygalacturonase (PG) activity, malondialdehyde (MDA) content, as well as enzyme activities and substances contents related to arginine catabolism were measured during ambient storage (23±2) ℃ for investigating the mechanism of SA on delaying postharvest senescence of kiwifruit. The results showed: (1) weight loss and firmness of SA treated fruit were 13.77% lower and 78.25% higher than that of control at 20 d, indicating that SA treatment effectively inhibited the decrease of firmness and fresh weight. (2) At 20 d, the PG activity of SApretreated fruit (13.61 μg·g^-1·h^-1) was significantly lower than that of the control (16.77 μg·g^-1·h^-1); The difference of MDA content in kiwifruit reached the maximum at 15 d of storage, and the MDA content of SA treatment was 33.40% lower than that of control. (3) Compared to control, SA treatment markedly improved the content of ornithine and the activities of arginine decarboxylase and ornithine decarboxylase. Meanwhile, SA treatment inhibited the activities of polyamine oxidase and diamine oxidase, and prominently increased the accumulation of polyamines (putrescine, spermine, spermidine) in kiwifruit during the whole storage. (4) In comparison with control fruit, SA treatment notably induced the enhancement of nitric oxide synthase activity in kiwifruit and promoted the accumulation of nitric oxide (NO) in fruit, and the content of NO in fruit was significantly higher than that of control after the 5 d of storage. The above results showed that SAmediated delay of postharvest senescence in kiwifruit at ambient storage, which may be associated with its trigger of different pathways of arginine catabolism.