The invention overcomes the defects of the traditional technical requirements such as high chowchow liquid concentration, and low chowchow liquid use ratio and processing efficiency, and discloses a preparation method of mango preserved fruit. By ensuring an exact ultrahigh pressure condition, the osmotic dehydration of the mango preserved fruit is accelerated to prepare low-sugar mango preserved fruit. The method is characterized in pressuring the mango by taking hydraulic pressure as a pressure transmission medium to sterilize, modify materiel, generate new organization structure and change the quality of the mango, so that the method has the characteristics of momentary compression, even reaction, safe operation and low energy consumption, and the prepared mango preserved fruit can well preserve the natural color smell and taste and the nutrition constituent of the mango, has special flavor, is sweet, tasty, refreshing and not greasy, has exquisite tissue, special taste and abundant nutrition, has abundant antioxidant components, is widely popularized, is particularly suitable for diabetes mellitus persons as the syrup is separated, and crates a new way for developing the edible and medical value of the mango.