The invention provides a soil improvement and orchard establishment method for a flat ground orchard. The method comprises steps as follows: (1) the whole orchard is shallowly ploughed by the depth being about 40 cm; (2) after the orchard is subjected to leveling treatment, 2,000-3,000 kg of special soil improvement fertilizer for fruit trees or biological organic fertilizer is applied to every mu of the whole orchard; (3) lines are drawn as per the double-row distance being 6.5-8 m, then ditches with the width and depth being 50-60 cm are dug, the width of ridge surfaces is 6-7.5 m, planting row lines are placed in positions 1.5 m away from ditch edges after the ridge surfaces are formed, and two planting row lines are placed for each ridge; or lines are drawn as per the row distance being 3.5-4.5 m, surface soil being 20 cm thick in the 1/2 range of the ridge surfaces is stacked onto soil in the other 1/2 range, shapes with the ditch width being 1.75-2.5 m, the ditch depth being 40 cm, the ridge surface width being 1.75-2.5 m and the ridge surface height being 40 cm are formed, ridges are straight and free from dislocation, and one row of fruit trees are planted on each ridge as per the plant distance. With the adoption of the method, the permeability of soil layers of the orchard can be improved, total nutrients and effective ingredients in the soil can be significantly improved, and growth of the fruit trees is facilitated; the yield and production value of the fruit trees in the orchard can be significantly increased; the method is particularly suitable for mechanical operation and is time-saving and labor-saving.