The work aims to prolong the freshness of grapes. The composite film with releasable SO2 in three layers was prepared. The composite film was hot sealed as packaging bag. The fresh-keeping packaging bag that released sulfur dioxide was analyzed. The fresh-keeping effect of fresh-keeping packaging bag on the grapes was studied at 23 ℃ by using the naked grapes as control group. Changes in the rates of mass loss, shattering and intact fruit, soluble solid content and hardness of grapes during storage were analyzed, and the appearances of grapes were observed. The fresh-keeping packaging bags could sustainably release 30 mg/L of SO2 for over 30 days. After 17 days' preservation at normal temperature, the naked grapes had lost their edible value and the intact fruit rate was 0%. And for the grapes in fresh-keeping packaging bags, the weight loss rate was 1.46%, shattering rate was 5.1% and intact fruit rate was approximately 60%. The SO2 slowly released by the composite film with releasable SO2 can be sustainably antibacterial and effectively prolong the shelf life of grapes.