The invention discloses a multi-adsorption-based environment-friendly water treatment finishing liquid. The finishing liquid is prepared from the following raw materials in parts by mass: 2-5 parts ofchitosan, 3-7 parts of sodium alginate, 80-100 parts of 2wt% acetic acid aqueous solution, 10-15 parts of gelatin, 2-3 parts of glutaraldehyde, 1-3 parts of hydrated rare earth oxide and 2-4 parts ofwhite carbon black. The invention also discloses a method for preparing a composite fabric by adopting the multi-adsorption-based environment-friendly water treatment finishing liquid as well as a water treatment device. The multi-adsorption-based environment-friendly water treatment finishing liquid has the advantages of high adsorption quantity and extensive objects.