Effects of different concentrations of 1-MCP on freshness of harvested Younai (Prunus salicina Lindl. cv. Younai）fruits were investigated. The harvested fruits were treated with 0, 0.3, 0.6, 0.9, 1.2μL/L 1-MCP for 12h, respectively, and then stored at （25±1）℃. During storage, the changes of respiration rate and cell membrane relative leakage rate of fruits, hue angle（h°）value of fruit surface, content of pericarp chlorophyll, fruit firmness, contents of total soluble solids and titratable acid of fruit, healthy fruit percentage, weight loss and organoleptic evaluation of quality of fruit were determined. The results showed that compared with the control fruits, the treatments with 1-MCP lowered respiration rate and respiratory peak, delayed the increase of cell membrane relative leakage rate , inhibited the decrease of hue angle（h°）value of fruit surface, kept higher fruit firmness, and kept higher contents of titratable acid in fruit and chlorophyll in pericarp, retarded the change of apparent color of fruit, and decreased fruit weight loss and fruit decay. Among the 1-MCP treated ones, the fruits treated with 1.2μL/L 1-MCP could keep best fruit quality. After storage at（25±1）℃ for 20d, the fruits still maintained fresh green with 87% as healthy fruit percentage, crisp and hard flesh, properly sour-sweet taste and rich aroma. It can be concluded that treatment with 1.2μL/L 1-MCP for 12h can be used as the optimum condition for maintaining fruit quality and prolonging storage life of Younai fruits during storage at (25±1)℃.