The invention belongs to the technical field of agricultural planting, and particularly relates to a method for cultivating a three-dimensional small open peach tree. The method comprises the following steps of: 1, raising the seedlings by using the cores of hill wild peaches, soaking the roots for 2-3 minutes by using root putrid before field planting, trimming the roots of diseases and insects,wrapping the roots by using yellow mud, and grafting the peaches seedlings by using a planting depth of 9-12 cm; 2, when the seedlings grow to 20cm after grafting, selecting three strong main branches, wherein the angle between the main branches and the ground is 65-75 degrees; 3, when the three main branches grow to 50-60cm, pinching for the first time; 4, pinching for the second time when the three main branches grow to 90-100cm; 5, spraying medicine, bagging and picking after the three-dimensional small and happy tree grows into a shape. According to the peach tree cultivation technology, the three-dimensional small happy type replacement head is adopted, so that the peach tree cultivation technology is uniform in dispersion, operation under the tree is facilitated, the ventilation effect is outstanding, the fruit quality is high and the growth is uniform.