The invention discloses a method for water-fed forestation in arid hillside fields of arid-hot river valleys, pertaining to the technical field of water-saving agriculture. The method comprises the steps of digging large ponds, backfilling prepared fertilizers, cultivating, strengthening and field planting seedlings, timely field planting against the rain in rain season, covering with grass to keep water, top dressing in rain season to promote the seedlings, wherein, the length, the width and the depth of the planting hole of an arbor tree is 120 cm multiplied by 80 cm multiplied by 100 cm while a frutescose tree is 80 cm multiplied by 50 cm multiplied by 60 cm and the planting hole is perpendicular to slope direction; when backfilling the soil, the soil in each pond is mixed with 5 kg to10 kg of organic fertilizer and 2 kg to 4 kg of mixed fertilizer of calcium, magnesium and phosphate fertilizers; field planting is carried out in May to June with sufficient rain water; after the field planting of nursery stocks, the weeds are cut in time for covering the tree pond; approximately 20 days after the field planting of the nursery stocks, quick effective nitrogen fertilizer is applied in proper time. Adoption of the method of the invention can enhance the survival ratio of forestation in arid hillside fields of arid-hot valleys under the circumstances of no irrigation water to more than 95 percent and the preservation rate to more than 90 percent. The technology of the invention is scientific, reasonable and feasible and has high significance in revegetation and ecological reconstruction of arid-hot river valleys.