The invention relates to a silty and fine sand slope protection method based on geonets and sand plants. Straw checkerboard barriers and planted and laid pebble slope protection are commonly adopted by wind-drift-sand roadbed slope protection to fix sand, however, the straw checkerboard barriers are short in service life, and the building and maintaining cost of the planted and laid pebble slope protection is high. According to the method, the geonets are laid on silty and fine sand slopes for earlier-stage mechanical sand fixing, and protection types of the laid geonets are selected from the following modes that a layer of CE131 geonet is directly laid on a silty and fine sand slope for protection; a screen window net is firstly laid on a silty and fine sand slope, and then a layer of CE152 geonet is laid in a pressing mode; a geonet mat is laid on a silty and fine sand slope; and the sand plants are planted on a silty and fine sand slope which is mechanically reinforced in advance, namely shrubs and herbaceous plants are combined. According to the method, the geonets are used as auxiliary materials for earlier-stage protection of the silty and fine sand slopes and protection of plant growth, and the method is not limited by natural conditions and has the advantages that material transportation is convenient, the construction speed is high, the labor intensity is reduced, and repairing and maintaining are convenient.