The invention belongs to the technical field of adhesives and relates to a preparation method of a layer-by-layer assembled adhesive film containing a small molecule inorganic salt. The layer-by-layer assembled adhesive film obtained by the layer-by-layer assembling technology has a refractive index in the range of 1.518 to 1.579, is transparent in the visible light area, does not go bad after being placed in air for 0.5 years, can be bonded under action of water and pressure without a UV curing process, and has bonding strength of 6.95+/-1.74 MPa. The adhesive can be dismantled through re-immersion in water and the whole process is finished in a water phase without contacting with an organic solvent. The layer-by-layer assembled adhesive film is environmentally friendly and is suitable for optical part bonding. The prepared layer-by-layer assembled adhesive film containing an inorganic salt has good stability at a temperature of 60 DEG C and under an extreme temperature condition of liquid nitrogen (at -190 DEG C).