Abstract: The softening phenomenon of postharvest fruit will occur after a series of processes such as storage and transportation, and there are many reasons for the occurrence. For example, the material composition and structure of the cell wall are changed due to the action of the enzyme activity related to cell wall metabolism. It may also be due to the changes of related substances after fruit ripening and the regulation of plant hormones, thus promoting fruit ripening and softening. In this paper, the causes of postharvest fruit softening are reviewed, including the synthesis of plant hormones and their binding to receptors to promote fruit softening, the regulation of related transcription factors on fruit softening, and the pathways of cell wall metabolism and carbohydrate metabolism related to fruit softening, in order to provide reference for exploring the mechanism of postharvest fruit softening.