In order to control the browning and quality deterioration of fresh-cut yam and extend its shelf life, By using the onion oil extracted from onion, which was combined with citric acid and chitosan, taking the L^* values and sensory score as index, the formula of compound preservative for fresh-cut yam was optimized by single factor and orthogonal experiments. The results showed that the optimal formula of preservative for fresh-cut yam was 0.6% onion oil + 1.0% citric acid + 1.0% chitosan. This formula could significantly inhibit the activities of polyphenol oxidase(PPO) and peroxidase(POD), reduce relative conductivity and the accumulation of MDA content, delay weight loss and softening, keep brightness and total phenol content, maintain the content of total soluble solid, soluble sugar and reducing sugar, and has better sensory quality. This formula extended the shelf life of fresh-cut yam about 6 d compared with the control group.