Abstract: In order to improve the fruit quality of Dongzao jujube in growth period, the effects of spraying HarpinXoo protein on fruit quality of Dongzao jujube tree in growth period were investigated. The experimental results indicated that spraying HarpinXoo protein can significantly increase the fruit weight, hardness, sugar-acid ratio, total sugar and vitamin C content, and reduce the rate of wound and diseases fruit. Compared to the control fruits sprayed with water, the fruit weight and hardness of the treatment fruits sprayed with HarpinXoo protein were increased by over 18.99% and 20.26%, the rate of wound and diseases fruit reduced by 59.67%. In early October, the sugar-acid ratio, total sugar and vitamin C content of the treatment fruits sprayed with HarpinXoo protein reached to 83.15, 33.26% and 4.76 mg/g, respectively, while those of the control fruits sprayed water were only 48.36, 20.31% and 3.41 mg/g, respectively. The fruit shape index, edible rate, moisture content and total acid content of the treatment fruits sprayed with HarpinXoo protein were well maintained. The appearance and taste quality of fruit were significantly improved by spraying HarpinXoo protein on Dongzao jujube tree in growth period. The suitable application concentration of HarpinXoo protein is 20 μg/mL. The research can provide a reference for improving the fruit quality of the Dongzao jujube in growth period.