The invention relates to the field of environment-friendly slope protection, in particular to a double-layer three-dimensional vegetation net greening and slope protection construction method appliedto fully-weathered rock slopes. The method includes steps: (1) laying a three-dimensional vegetation net on a fully-weathered rock slope in advance, covering with a first soil layer which is preventedfrom slipping and losing by a network structure of the three-dimensional vegetation net, laying a second three-dimensional vegetation net on the first soil layer to form an interlayer structure withthe first net, covering with a second soil layer after preliminary operations are finished, spreading grass seeds, covering the grass seeds with a thin humus layer, covering with grass mats, and watering for maintenance; (2) in laying of the two layers of the three-dimensional vegetation nets, adopting reinforcing steel bars for making 'U'-shaped ground pegs for fixing; if the slope is steep, before laying of the second soil layer, latticing the well laid and fixed second three-dimensional vegetation net by battens to well prevent the second soil layer from slipping towards the toe of the slope. Therefore, greening and slope stabilization are realized, and water and soil loss is prevented.