‘Egan No.1’ Ponkan was used to study the effects of mechanical pruning-mediated fruit thinning on improving fruit quality to find a labor-saving way for thinning fruit in a more efficient manner.At the same time，the expression patterns of genes associated with sucrose and citric acid metabolism were analyzed.The results showed that the fruit thinning speed and efficiency were substantially accelerated by mechanical pruning，leading to significant labor-saving.In addition，mechanical pruning-mediated fruit thinning significantly increased the transverse diameters，longitudinal diameters，single fruit weight and fruit firmness of the Ponkan fruit.Meanwhile，the proportion of large-sized fruit at the stage of ripening was significantly increased to 57%.Mechanical pruning-mediated fruit thinning accelerated the color change of fruit peel，significantly increased total soluble solids to 11.57% and reduced the content of titratable acids.The content of sucrose was significantly increased to 52.10 mg/g.The result of quantitative real-time PCR showed that genes involved in the synthesis of sucrose and the degradation of citric acid were significantly up-regulated in the fruits collected from the thinned trees in comparison with the unthinned trees.Mechanical pruning-mediated fruit thinning can be used as a labor-saving fruit thinning method to improve the quality of Ponkan fruit by up-regulating genes associated with the synthesis of sucrose and the degradation of citric acid.